use std::collections::BTreeSet;
use std::time::{Duration, Instant};

use reqwest::blocking::Client;
use runtime::{
    edit_file, execute_bash, glob_search, grep_search, read_file, write_file, BashCommandInput,
    GrepSearchInput,
};
use serde::{Deserialize, Serialize};
use serde_json::{json, Value};

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ToolManifestEntry {
    pub name: String,
    pub source: ToolSource,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ToolSource {
    Base,
    Conditional,
}

#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct ToolRegistry {
    entries: Vec<ToolManifestEntry>,
}

impl ToolRegistry {
    #[must_use]
    pub fn new(entries: Vec<ToolManifestEntry>) -> Self {
        Self { entries }
    }

    #[must_use]
    pub fn entries(&self) -> &[ToolManifestEntry] {
        &self.entries
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ToolSpec {
    pub name: &'static str,
    pub description: &'static str,
    pub input_schema: Value,
}

#[must_use]
pub fn mvp_tool_specs() -> Vec<ToolSpec> {
    vec![
        ToolSpec {
            name: "bash",
            description: "Execute a shell command in the current workspace.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "command": { "type": "string" },
                    "timeout": { "type": "integer", "minimum": 1 },
                    "description": { "type": "string" },
                    "run_in_background": { "type": "boolean" },
                    "dangerouslyDisableSandbox": { "type": "boolean" }
                },
                "required": ["command"],
                "additionalProperties": false
            }),
        },
        ToolSpec {
            name: "read_file",
            description: "Read a text file from the workspace.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "path": { "type": "string" },
                    "offset": { "type": "integer", "minimum": 0 },
                    "limit": { "type": "integer", "minimum": 1 }
                },
                "required": ["path"],
                "additionalProperties": false
            }),
        },
        ToolSpec {
            name: "write_file",
            description: "Write a text file in the workspace.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "path": { "type": "string" },
                    "content": { "type": "string" }
                },
                "required": ["path", "content"],
                "additionalProperties": false
            }),
        },
        ToolSpec {
            name: "edit_file",
            description: "Replace text in a workspace file.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "path": { "type": "string" },
                    "old_string": { "type": "string" },
                    "new_string": { "type": "string" },
                    "replace_all": { "type": "boolean" }
                },
                "required": ["path", "old_string", "new_string"],
                "additionalProperties": false
            }),
        },
        ToolSpec {
            name: "glob_search",
            description: "Find files by glob pattern.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "pattern": { "type": "string" },
                    "path": { "type": "string" }
                },
                "required": ["pattern"],
                "additionalProperties": false
            }),
        },
        ToolSpec {
            name: "grep_search",
            description: "Search file contents with a regex pattern.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "pattern": { "type": "string" },
                    "path": { "type": "string" },
                    "glob": { "type": "string" },
                    "output_mode": { "type": "string" },
                    "-B": { "type": "integer", "minimum": 0 },
                    "-A": { "type": "integer", "minimum": 0 },
                    "-C": { "type": "integer", "minimum": 0 },
                    "context": { "type": "integer", "minimum": 0 },
                    "-n": { "type": "boolean" },
                    "-i": { "type": "boolean" },
                    "type": { "type": "string" },
                    "head_limit": { "type": "integer", "minimum": 1 },
                    "offset": { "type": "integer", "minimum": 0 },
                    "multiline": { "type": "boolean" }
                },
                "required": ["pattern"],
                "additionalProperties": false
            }),
        },
        ToolSpec {
            name: "WebFetch",
            description:
                "Fetch a URL, convert it into readable text, and answer a prompt about it.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "url": { "type": "string", "format": "uri" },
                    "prompt": { "type": "string" }
                },
                "required": ["url", "prompt"],
                "additionalProperties": false
            }),
        },
        ToolSpec {
            name: "WebSearch",
            description: "Search the web for current information and return cited results.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "query": { "type": "string", "minLength": 2 },
                    "allowed_domains": {
                        "type": "array",
                        "items": { "type": "string" }
                    },
                    "blocked_domains": {
                        "type": "array",
                        "items": { "type": "string" }
                    }
                },
                "required": ["query"],
                "additionalProperties": false
            }),
        },
        ToolSpec {
            name: "TodoWrite",
            description: "Update the structured task list for the current session.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "todos": {
                        "type": "array",
                        "items": {
                            "type": "object",
                            "properties": {
                                "content": { "type": "string" },
                                "activeForm": { "type": "string" },
                                "status": {
                                    "type": "string",
                                    "enum": ["pending", "in_progress", "completed"]
                                }
                            },
                            "required": ["content", "activeForm", "status"],
                            "additionalProperties": false
                        }
                    }
                },
                "required": ["todos"],
                "additionalProperties": false
            }),
        },
        ToolSpec {
            name: "Skill",
            description: "Load a local skill definition and its instructions.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "skill": { "type": "string" },
                    "args": { "type": "string" }
                },
                "required": ["skill"],
                "additionalProperties": false
            }),
        },
    ]
}

pub fn execute_tool(name: &str, input: &Value) -> Result<String, String> {
    match name {
        "bash" => from_value::<BashCommandInput>(input).and_then(run_bash),
        "read_file" => from_value::<ReadFileInput>(input).and_then(run_read_file),
        "write_file" => from_value::<WriteFileInput>(input).and_then(run_write_file),
        "edit_file" => from_value::<EditFileInput>(input).and_then(run_edit_file),
        "glob_search" => from_value::<GlobSearchInputValue>(input).and_then(run_glob_search),
        "grep_search" => from_value::<GrepSearchInput>(input).and_then(run_grep_search),
        "WebFetch" => from_value::<WebFetchInput>(input).and_then(run_web_fetch),
        "WebSearch" => from_value::<WebSearchInput>(input).and_then(run_web_search),
        "TodoWrite" => from_value::<TodoWriteInput>(input).and_then(run_todo_write),
        "Skill" => from_value::<SkillInput>(input).and_then(run_skill),
        _ => Err(format!("unsupported tool: {name}")),
    }
}

fn from_value<T: for<'de> Deserialize<'de>>(input: &Value) -> Result<T, String> {
    serde_json::from_value(input.clone()).map_err(|error| error.to_string())
}

fn run_bash(input: BashCommandInput) -> Result<String, String> {
    serde_json::to_string_pretty(&execute_bash(input).map_err(|error| error.to_string())?)
        .map_err(|error| error.to_string())
}

fn run_read_file(input: ReadFileInput) -> Result<String, String> {
    to_pretty_json(read_file(&input.path, input.offset, input.limit).map_err(io_to_string)?)
}

fn run_write_file(input: WriteFileInput) -> Result<String, String> {
    to_pretty_json(write_file(&input.path, &input.content).map_err(io_to_string)?)
}

fn run_edit_file(input: EditFileInput) -> Result<String, String> {
    to_pretty_json(
        edit_file(
            &input.path,
            &input.old_string,
            &input.new_string,
            input.replace_all.unwrap_or(false),
        )
        .map_err(io_to_string)?,
    )
}

fn run_glob_search(input: GlobSearchInputValue) -> Result<String, String> {
    to_pretty_json(glob_search(&input.pattern, input.path.as_deref()).map_err(io_to_string)?)
}

fn run_grep_search(input: GrepSearchInput) -> Result<String, String> {
    to_pretty_json(grep_search(&input).map_err(io_to_string)?)
}

fn run_web_fetch(input: WebFetchInput) -> Result<String, String> {
    to_pretty_json(execute_web_fetch(&input)?)
}

fn run_web_search(input: WebSearchInput) -> Result<String, String> {
    to_pretty_json(execute_web_search(&input)?)
}

fn run_todo_write(input: TodoWriteInput) -> Result<String, String> {
    to_pretty_json(execute_todo_write(input)?)
}

fn run_skill(input: SkillInput) -> Result<String, String> {
    to_pretty_json(execute_skill(input)?)
}

fn to_pretty_json<T: serde::Serialize>(value: T) -> Result<String, String> {
    serde_json::to_string_pretty(&value).map_err(|error| error.to_string())
}

fn io_to_string(error: std::io::Error) -> String {
    error.to_string()
}

#[derive(Debug, Deserialize)]
struct ReadFileInput {
    path: String,
    offset: Option<usize>,
    limit: Option<usize>,
}

#[derive(Debug, Deserialize)]
struct WriteFileInput {
    path: String,
    content: String,
}

#[derive(Debug, Deserialize)]
struct EditFileInput {
    path: String,
    old_string: String,
    new_string: String,
    replace_all: Option<bool>,
}

#[derive(Debug, Deserialize)]
struct GlobSearchInputValue {
    pattern: String,
    path: Option<String>,
}

#[derive(Debug, Deserialize)]
struct WebFetchInput {
    url: String,
    prompt: String,
}

#[derive(Debug, Deserialize)]
struct WebSearchInput {
    query: String,
    allowed_domains: Option<Vec<String>>,
    blocked_domains: Option<Vec<String>>,
}

#[derive(Debug, Deserialize)]
struct TodoWriteInput {
    todos: Vec<TodoItem>,
}

#[derive(Debug, Deserialize, Serialize, Clone, PartialEq, Eq)]
struct TodoItem {
    content: String,
    #[serde(rename = "activeForm")]
    active_form: String,
    status: TodoStatus,
}

#[derive(Debug, Deserialize, Serialize, Clone, PartialEq, Eq)]
#[serde(rename_all = "snake_case")]
enum TodoStatus {
    Pending,
    InProgress,
    Completed,
}

#[derive(Debug, Deserialize)]
struct SkillInput {
    skill: String,
    args: Option<String>,
}

#[derive(Debug, Serialize)]
struct WebFetchOutput {
    bytes: usize,
    code: u16,
    #[serde(rename = "codeText")]
    code_text: String,
    result: String,
    #[serde(rename = "durationMs")]
    duration_ms: u128,
    url: String,
}

#[derive(Debug, Serialize)]
struct WebSearchOutput {
    query: String,
    results: Vec<WebSearchResultItem>,
    #[serde(rename = "durationSeconds")]
    duration_seconds: f64,
}

#[derive(Debug, Serialize)]
struct TodoWriteOutput {
    #[serde(rename = "oldTodos")]
    old_todos: Vec<TodoItem>,
    #[serde(rename = "newTodos")]
    new_todos: Vec<TodoItem>,
    #[serde(rename = "verificationNudgeNeeded")]
    verification_nudge_needed: Option<bool>,
}

#[derive(Debug, Serialize)]
struct SkillOutput {
    skill: String,
    path: String,
    args: Option<String>,
    description: Option<String>,
    prompt: String,
}

#[derive(Debug, Serialize)]
#[serde(untagged)]
enum WebSearchResultItem {
    SearchResult {
        tool_use_id: String,
        content: Vec<SearchHit>,
    },
    Commentary(String),
}

#[derive(Debug, Serialize)]
struct SearchHit {
    title: String,
    url: String,
}

fn execute_web_fetch(input: &WebFetchInput) -> Result<WebFetchOutput, String> {
    let started = Instant::now();
    let client = build_http_client()?;
    let request_url = normalize_fetch_url(&input.url)?;
    let response = client
        .get(request_url.clone())
        .send()
        .map_err(|error| error.to_string())?;

    let status = response.status();
    let final_url = response.url().to_string();
    let code = status.as_u16();
    let code_text = status.canonical_reason().unwrap_or("Unknown").to_string();
    let content_type = response
        .headers()
        .get(reqwest::header::CONTENT_TYPE)
        .and_then(|value| value.to_str().ok())
        .unwrap_or_default()
        .to_string();
    let body = response.text().map_err(|error| error.to_string())?;
    let bytes = body.len();
    let normalized = normalize_fetched_content(&body, &content_type);
    let result = summarize_web_fetch(&final_url, &input.prompt, &normalized);

    Ok(WebFetchOutput {
        bytes,
        code,
        code_text,
        result,
        duration_ms: started.elapsed().as_millis(),
        url: final_url,
    })
}

fn execute_web_search(input: &WebSearchInput) -> Result<WebSearchOutput, String> {
    let started = Instant::now();
    let client = build_http_client()?;
    let search_url = build_search_url(&input.query)?;
    let response = client
        .get(search_url)
        .send()
        .map_err(|error| error.to_string())?;

    let final_url = response.url().clone();
    let html = response.text().map_err(|error| error.to_string())?;
    let mut hits = extract_search_hits(&html);

    if hits.is_empty() && final_url.host_str().is_some() {
        hits = extract_search_hits_from_generic_links(&html);
    }

    if let Some(allowed) = input.allowed_domains.as_ref() {
        hits.retain(|hit| host_matches_list(&hit.url, allowed));
    }
    if let Some(blocked) = input.blocked_domains.as_ref() {
        hits.retain(|hit| !host_matches_list(&hit.url, blocked));
    }

    dedupe_hits(&mut hits);
    hits.truncate(8);

    let summary = if hits.is_empty() {
        format!("No web search results matched the query {:?}.", input.query)
    } else {
        let rendered_hits = hits
            .iter()
            .map(|hit| format!("- [{}]({})", hit.title, hit.url))
            .collect::<Vec<_>>()
            .join("\n");
        format!(
            "Search results for {:?}. Include a Sources section in the final answer.\n{}",
            input.query, rendered_hits
        )
    };

    Ok(WebSearchOutput {
        query: input.query.clone(),
        results: vec![
            WebSearchResultItem::Commentary(summary),
            WebSearchResultItem::SearchResult {
                tool_use_id: String::from("web_search_1"),
                content: hits,
            },
        ],
        duration_seconds: started.elapsed().as_secs_f64(),
    })
}

fn build_http_client() -> Result<Client, String> {
    Client::builder()
        .timeout(Duration::from_secs(20))
        .redirect(reqwest::redirect::Policy::limited(10))
        .user_agent("clawd-rust-tools/0.1")
        .build()
        .map_err(|error| error.to_string())
}

fn normalize_fetch_url(url: &str) -> Result<String, String> {
    let parsed = reqwest::Url::parse(url).map_err(|error| error.to_string())?;
    if parsed.scheme() == "http" {
        let host = parsed.host_str().unwrap_or_default();
        if host != "localhost" && host != "127.0.0.1" && host != "::1" {
            let mut upgraded = parsed;
            upgraded
                .set_scheme("https")
                .map_err(|_| String::from("failed to upgrade URL to https"))?;
            return Ok(upgraded.to_string());
        }
    }
    Ok(parsed.to_string())
}

fn build_search_url(query: &str) -> Result<reqwest::Url, String> {
    if let Ok(base) = std::env::var("CLAWD_WEB_SEARCH_BASE_URL") {
        let mut url = reqwest::Url::parse(&base).map_err(|error| error.to_string())?;
        url.query_pairs_mut().append_pair("q", query);
        return Ok(url);
    }

    let mut url = reqwest::Url::parse("https://html.duckduckgo.com/html/")
        .map_err(|error| error.to_string())?;
    url.query_pairs_mut().append_pair("q", query);
    Ok(url)
}

fn normalize_fetched_content(body: &str, content_type: &str) -> String {
    if content_type.contains("html") {
        html_to_text(body)
    } else {
        body.trim().to_string()
    }
}

fn summarize_web_fetch(url: &str, prompt: &str, content: &str) -> String {
    let lower_prompt = prompt.to_lowercase();
    let compact = collapse_whitespace(content);

    let detail = if lower_prompt.contains("title") {
        extract_title(content)
            .map(|title| format!("Title: {title}"))
            .unwrap_or_else(|| preview_text(&compact, 600))
    } else if lower_prompt.contains("summary") || lower_prompt.contains("summarize") {
        preview_text(&compact, 900)
    } else {
        let preview = preview_text(&compact, 900);
        format!("Prompt: {prompt}\nContent preview:\n{preview}")
    };

    format!("Fetched {url}\n{detail}")
}

fn extract_title(content: &str) -> Option<String> {
    for line in content.lines() {
        let trimmed = line.trim();
        if !trimmed.is_empty() {
            return Some(trimmed.to_string());
        }
    }
    None
}

fn html_to_text(html: &str) -> String {
    let mut text = String::with_capacity(html.len());
    let mut in_tag = false;
    let mut previous_was_space = false;

    for ch in html.chars() {
        match ch {
            '<' => in_tag = true,
            '>' => in_tag = false,
            _ if in_tag => {}
            '&' => {
                text.push('&');
                previous_was_space = false;
            }
            ch if ch.is_whitespace() => {
                if !previous_was_space {
                    text.push(' ');
                    previous_was_space = true;
                }
            }
            _ => {
                text.push(ch);
                previous_was_space = false;
            }
        }
    }

    collapse_whitespace(&decode_html_entities(&text))
}

fn decode_html_entities(input: &str) -> String {
    input
        .replace("&amp;", "&")
        .replace("&lt;", "<")
        .replace("&gt;", ">")
        .replace("&quot;", "\"")
        .replace("&#39;", "'")
        .replace("&nbsp;", " ")
}

fn collapse_whitespace(input: &str) -> String {
    input.split_whitespace().collect::<Vec<_>>().join(" ")
}

fn preview_text(input: &str, max_chars: usize) -> String {
    if input.chars().count() <= max_chars {
        return input.to_string();
    }
    let shortened = input.chars().take(max_chars).collect::<String>();
    format!("{}…", shortened.trim_end())
}

fn extract_search_hits(html: &str) -> Vec<SearchHit> {
    let mut hits = Vec::new();
    let mut remaining = html;

    while let Some(anchor_start) = remaining.find("result__a") {
        let after_class = &remaining[anchor_start..];
        let Some(href_idx) = after_class.find("href=") else {
            remaining = &after_class[1..];
            continue;
        };
        let href_slice = &after_class[href_idx + 5..];
        let Some((url, rest)) = extract_quoted_value(href_slice) else {
            remaining = &after_class[1..];
            continue;
        };
        let Some(close_tag_idx) = rest.find('>') else {
            remaining = &after_class[1..];
            continue;
        };
        let after_tag = &rest[close_tag_idx + 1..];
        let Some(end_anchor_idx) = after_tag.find("</a>") else {
            remaining = &after_tag[1..];
            continue;
        };
        let title = html_to_text(&after_tag[..end_anchor_idx]);
        if let Some(decoded_url) = decode_duckduckgo_redirect(&url) {
            hits.push(SearchHit {
                title: title.trim().to_string(),
                url: decoded_url,
            });
        }
        remaining = &after_tag[end_anchor_idx + 4..];
    }

    hits
}

fn extract_search_hits_from_generic_links(html: &str) -> Vec<SearchHit> {
    let mut hits = Vec::new();
    let mut remaining = html;

    while let Some(anchor_start) = remaining.find("<a") {
        let after_anchor = &remaining[anchor_start..];
        let Some(href_idx) = after_anchor.find("href=") else {
            remaining = &after_anchor[2..];
            continue;
        };
        let href_slice = &after_anchor[href_idx + 5..];
        let Some((url, rest)) = extract_quoted_value(href_slice) else {
            remaining = &after_anchor[2..];
            continue;
        };
        let Some(close_tag_idx) = rest.find('>') else {
            remaining = &after_anchor[2..];
            continue;
        };
        let after_tag = &rest[close_tag_idx + 1..];
        let Some(end_anchor_idx) = after_tag.find("</a>") else {
            remaining = &after_anchor[2..];
            continue;
        };
        let title = html_to_text(&after_tag[..end_anchor_idx]);
        if title.trim().is_empty() {
            remaining = &after_tag[end_anchor_idx + 4..];
            continue;
        }
        let decoded_url = decode_duckduckgo_redirect(&url).unwrap_or(url);
        if decoded_url.starts_with("http://") || decoded_url.starts_with("https://") {
            hits.push(SearchHit {
                title: title.trim().to_string(),
                url: decoded_url,
            });
        }
        remaining = &after_tag[end_anchor_idx + 4..];
    }

    hits
}

fn extract_quoted_value(input: &str) -> Option<(String, &str)> {
    let quote = input.chars().next()?;
    if quote != '"' && quote != '\'' {
        return None;
    }
    let rest = &input[quote.len_utf8()..];
    let end = rest.find(quote)?;
    Some((rest[..end].to_string(), &rest[end + quote.len_utf8()..]))
}

fn decode_duckduckgo_redirect(url: &str) -> Option<String> {
    if url.starts_with("http://") || url.starts_with("https://") {
        return Some(html_entity_decode_url(url));
    }

    let joined = if url.starts_with("//") {
        format!("https:{url}")
    } else if url.starts_with('/') {
        format!("https://duckduckgo.com{url}")
    } else {
        return None;
    };

    let parsed = reqwest::Url::parse(&joined).ok()?;
    if parsed.path() == "/l/" || parsed.path() == "/l" {
        for (key, value) in parsed.query_pairs() {
            if key == "uddg" {
                return Some(html_entity_decode_url(value.as_ref()));
            }
        }
    }
    Some(joined)
}

fn html_entity_decode_url(url: &str) -> String {
    decode_html_entities(url)
}

fn host_matches_list(url: &str, domains: &[String]) -> bool {
    let Ok(parsed) = reqwest::Url::parse(url) else {
        return false;
    };
    let Some(host) = parsed.host_str() else {
        return false;
    };
    domains.iter().any(|domain| {
        let normalized = domain.trim().trim_start_matches('.');
        host == normalized || host.ends_with(&format!(".{normalized}"))
    })
}

fn dedupe_hits(hits: &mut Vec<SearchHit>) {
    let mut seen = BTreeSet::new();
    hits.retain(|hit| seen.insert(hit.url.clone()));
}

fn execute_todo_write(input: TodoWriteInput) -> Result<TodoWriteOutput, String> {
    validate_todos(&input.todos)?;
    let store_path = todo_store_path()?;
    let old_todos = if store_path.exists() {
        serde_json::from_str::<Vec<TodoItem>>(
            &std::fs::read_to_string(&store_path).map_err(|error| error.to_string())?,
        )
        .map_err(|error| error.to_string())?
    } else {
        Vec::new()
    };

    let all_done = input
        .todos
        .iter()
        .all(|todo| matches!(todo.status, TodoStatus::Completed));
    let persisted = if all_done {
        Vec::new()
    } else {
        input.todos.clone()
    };

    if let Some(parent) = store_path.parent() {
        std::fs::create_dir_all(parent).map_err(|error| error.to_string())?;
    }
    std::fs::write(
        &store_path,
        serde_json::to_string_pretty(&persisted).map_err(|error| error.to_string())?,
    )
    .map_err(|error| error.to_string())?;

    let verification_nudge_needed = (all_done
        && input.todos.len() >= 3
        && !input
            .todos
            .iter()
            .any(|todo| todo.content.to_lowercase().contains("verif")))
    .then_some(true);

    Ok(TodoWriteOutput {
        old_todos,
        new_todos: input.todos,
        verification_nudge_needed,
    })
}

fn execute_skill(input: SkillInput) -> Result<SkillOutput, String> {
    let skill_path = resolve_skill_path(&input.skill)?;
    let prompt = std::fs::read_to_string(&skill_path).map_err(|error| error.to_string())?;
    let description = parse_skill_description(&prompt);

    Ok(SkillOutput {
        skill: input.skill,
        path: skill_path.display().to_string(),
        args: input.args,
        description,
        prompt,
    })
}

fn validate_todos(todos: &[TodoItem]) -> Result<(), String> {
    if todos.is_empty() {
        return Err(String::from("todos must not be empty"));
    }
    let in_progress = todos
        .iter()
        .filter(|todo| matches!(todo.status, TodoStatus::InProgress))
        .count();
    if in_progress > 1 {
        return Err(String::from(
            "exactly zero or one todo items may be in_progress",
        ));
    }
    if todos.iter().any(|todo| todo.content.trim().is_empty()) {
        return Err(String::from("todo content must not be empty"));
    }
    if todos.iter().any(|todo| todo.active_form.trim().is_empty()) {
        return Err(String::from("todo activeForm must not be empty"));
    }
    Ok(())
}

fn todo_store_path() -> Result<std::path::PathBuf, String> {
    if let Ok(path) = std::env::var("CLAWD_TODO_STORE") {
        return Ok(std::path::PathBuf::from(path));
    }
    let cwd = std::env::current_dir().map_err(|error| error.to_string())?;
    Ok(cwd.join(".clawd-todos.json"))
}

fn resolve_skill_path(skill: &str) -> Result<std::path::PathBuf, String> {
    let requested = skill.trim().trim_start_matches('/');
    if requested.is_empty() {
        return Err(String::from("skill must not be empty"));
    }

    let mut candidates = Vec::new();
    if let Ok(codex_home) = std::env::var("CODEX_HOME") {
        candidates.push(std::path::PathBuf::from(codex_home).join("skills"));
    }
    candidates.push(std::path::PathBuf::from("/home/bellman/.codex/skills"));

    for root in candidates {
        let direct = root.join(requested).join("SKILL.md");
        if direct.exists() {
            return Ok(direct);
        }

        if let Ok(entries) = std::fs::read_dir(&root) {
            for entry in entries.flatten() {
                let path = entry.path().join("SKILL.md");
                if !path.exists() {
                    continue;
                }
                if entry
                    .file_name()
                    .to_string_lossy()
                    .eq_ignore_ascii_case(requested)
                {
                    return Ok(path);
                }
            }
        }
    }

    Err(format!("unknown skill: {requested}"))
}

fn parse_skill_description(contents: &str) -> Option<String> {
    for line in contents.lines() {
        if let Some(value) = line.strip_prefix("description:") {
            let trimmed = value.trim();
            if !trimmed.is_empty() {
                return Some(trimmed.to_string());
            }
        }
    }
    None
}

#[cfg(test)]
mod tests {
    use std::io::{Read, Write};
    use std::net::{SocketAddr, TcpListener};
    use std::sync::Arc;
    use std::thread;
    use std::time::Duration;

    use super::{execute_tool, mvp_tool_specs};
    use serde_json::json;

    #[test]
    fn exposes_mvp_tools() {
        let names = mvp_tool_specs()
            .into_iter()
            .map(|spec| spec.name)
            .collect::<Vec<_>>();
        assert!(names.contains(&"bash"));
        assert!(names.contains(&"read_file"));
        assert!(names.contains(&"WebFetch"));
        assert!(names.contains(&"WebSearch"));
    }

    #[test]
    fn rejects_unknown_tool_names() {
        let error = execute_tool("nope", &json!({})).expect_err("tool should be rejected");
        assert!(error.contains("unsupported tool"));
    }

    #[test]
    fn web_fetch_returns_prompt_aware_summary() {
        let server = TestServer::spawn(Arc::new(|request_line: &str| {
            assert!(request_line.starts_with("GET /page "));
            HttpResponse::html(
                200,
                "OK",
                "<html><head><title>Ignored</title></head><body><h1>Test Page</h1><p>Hello <b>world</b> from local server.</p></body></html>",
            )
        }));

        let result = execute_tool(
            "WebFetch",
            &json!({
                "url": format!("http://{}/page", server.addr()),
                "prompt": "Summarize this page"
            }),
        )
        .expect("WebFetch should succeed");

        let output: serde_json::Value = serde_json::from_str(&result).expect("valid json");
        assert_eq!(output["code"], 200);
        let summary = output["result"].as_str().expect("result string");
        assert!(summary.contains("Fetched"));
        assert!(summary.contains("Test Page"));
        assert!(summary.contains("Hello world from local server"));
    }

    #[test]
    fn web_search_extracts_and_filters_results() {
        let server = TestServer::spawn(Arc::new(|request_line: &str| {
            assert!(request_line.contains("GET /search?q=rust+web+search "));
            HttpResponse::html(
                200,
                "OK",
                r#"
                <html><body>
                  <a class="result__a" href="https://docs.rs/reqwest">Reqwest docs</a>
                  <a class="result__a" href="https://example.com/blocked">Blocked result</a>
                </body></html>
                "#,
            )
        }));

        std::env::set_var(
            "CLAWD_WEB_SEARCH_BASE_URL",
            format!("http://{}/search", server.addr()),
        );
        let result = execute_tool(
            "WebSearch",
            &json!({
                "query": "rust web search",
                "allowed_domains": ["docs.rs"],
                "blocked_domains": ["example.com"]
            }),
        )
        .expect("WebSearch should succeed");
        std::env::remove_var("CLAWD_WEB_SEARCH_BASE_URL");

        let output: serde_json::Value = serde_json::from_str(&result).expect("valid json");
        assert_eq!(output["query"], "rust web search");
        let results = output["results"].as_array().expect("results array");
        let search_result = results
            .iter()
            .find(|item| item.get("content").is_some())
            .expect("search result block present");
        let content = search_result["content"].as_array().expect("content array");
        assert_eq!(content.len(), 1);
        assert_eq!(content[0]["title"], "Reqwest docs");
        assert_eq!(content[0]["url"], "https://docs.rs/reqwest");
    }

    #[test]
    fn todo_write_persists_and_returns_previous_state() {
        let path = std::env::temp_dir().join(format!(
            "clawd-tools-todos-{}.json",
            std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("time")
                .as_nanos()
        ));
        std::env::set_var("CLAWD_TODO_STORE", &path);

        let first = execute_tool(
            "TodoWrite",
            &json!({
                "todos": [
                    {"content": "Add tool", "activeForm": "Adding tool", "status": "in_progress"},
                    {"content": "Run tests", "activeForm": "Running tests", "status": "pending"}
                ]
            }),
        )
        .expect("TodoWrite should succeed");
        let first_output: serde_json::Value = serde_json::from_str(&first).expect("valid json");
        assert_eq!(first_output["oldTodos"].as_array().expect("array").len(), 0);

        let second = execute_tool(
            "TodoWrite",
            &json!({
                "todos": [
                    {"content": "Add tool", "activeForm": "Adding tool", "status": "completed"},
                    {"content": "Run tests", "activeForm": "Running tests", "status": "completed"},
                    {"content": "Verify", "activeForm": "Verifying", "status": "completed"}
                ]
            }),
        )
        .expect("TodoWrite should succeed");
        std::env::remove_var("CLAWD_TODO_STORE");
        let _ = std::fs::remove_file(path);

        let second_output: serde_json::Value = serde_json::from_str(&second).expect("valid json");
        assert_eq!(
            second_output["oldTodos"].as_array().expect("array").len(),
            2
        );
        assert_eq!(
            second_output["newTodos"].as_array().expect("array").len(),
            3
        );
        assert!(second_output["verificationNudgeNeeded"].is_null());
    }

    #[test]
    fn skill_loads_local_skill_prompt() {
        let result = execute_tool(
            "Skill",
            &json!({
                "skill": "help",
                "args": "overview"
            }),
        )
        .expect("Skill should succeed");

        let output: serde_json::Value = serde_json::from_str(&result).expect("valid json");
        assert_eq!(output["skill"], "help");
        assert!(output["path"]
            .as_str()
            .expect("path")
            .ends_with("/help/SKILL.md"));
        assert!(output["prompt"]
            .as_str()
            .expect("prompt")
            .contains("Guide on using oh-my-codex plugin"));
    }

    struct TestServer {
        addr: SocketAddr,
        shutdown: Option<std::sync::mpsc::Sender<()>>,
        handle: Option<thread::JoinHandle<()>>,
    }

    impl TestServer {
        fn spawn(handler: Arc<dyn Fn(&str) -> HttpResponse + Send + Sync + 'static>) -> Self {
            let listener = TcpListener::bind("127.0.0.1:0").expect("bind test server");
            listener
                .set_nonblocking(true)
                .expect("set nonblocking listener");
            let addr = listener.local_addr().expect("local addr");
            let (tx, rx) = std::sync::mpsc::channel::<()>();

            let handle = thread::spawn(move || loop {
                if rx.try_recv().is_ok() {
                    break;
                }

                match listener.accept() {
                    Ok((mut stream, _)) => {
                        let mut buffer = [0_u8; 4096];
                        let size = stream.read(&mut buffer).expect("read request");
                        let request = String::from_utf8_lossy(&buffer[..size]).into_owned();
                        let request_line = request.lines().next().unwrap_or_default().to_string();
                        let response = handler(&request_line);
                        stream
                            .write_all(response.to_bytes().as_slice())
                            .expect("write response");
                    }
                    Err(error) if error.kind() == std::io::ErrorKind::WouldBlock => {
                        thread::sleep(Duration::from_millis(10));
                    }
                    Err(error) => panic!("server accept failed: {error}"),
                }
            });

            Self {
                addr,
                shutdown: Some(tx),
                handle: Some(handle),
            }
        }

        fn addr(&self) -> SocketAddr {
            self.addr
        }
    }

    impl Drop for TestServer {
        fn drop(&mut self) {
            if let Some(tx) = self.shutdown.take() {
                let _ = tx.send(());
            }
            if let Some(handle) = self.handle.take() {
                handle.join().expect("join test server");
            }
        }
    }

    struct HttpResponse {
        status: u16,
        reason: &'static str,
        content_type: &'static str,
        body: String,
    }

    impl HttpResponse {
        fn html(status: u16, reason: &'static str, body: &str) -> Self {
            Self {
                status,
                reason,
                content_type: "text/html; charset=utf-8",
                body: body.to_string(),
            }
        }

        fn to_bytes(&self) -> Vec<u8> {
            format!(
                "HTTP/1.1 {} {}\r\nContent-Type: {}\r\nContent-Length: {}\r\nConnection: close\r\n\r\n{}",
                self.status,
                self.reason,
                self.content_type,
                self.body.len(),
                self.body
            )
            .into_bytes()
        }
    }
}