//! Bot-level command registry for the Matrix bot.
//!
//! Commands registered here are handled directly by the bot without invoking
//! the LLM. The registry is the single source of truth — the `help` command
//! iterates it automatically so new commands appear in the help output as soon
//! as they are added.

use crate::agents::{AgentPool, AgentStatus};
use crate::config::ProjectConfig;
use matrix_sdk::ruma::OwnedRoomId;
use std::collections::HashSet;
use std::path::Path;
use std::sync::{Arc, Mutex};

use super::config::save_ambient_rooms;

/// A bot-level command that is handled without LLM invocation.
pub struct BotCommand {
    /// The command keyword (e.g., `"help"`). Always lowercase.
    pub name: &'static str,
    /// Short description shown in help output.
    pub description: &'static str,
    /// Handler that produces the response text (Markdown), or `None` to fall
    /// through to the LLM (e.g. when a command requires direct addressing but
    /// the message arrived via ambient mode).
    pub handler: fn(&CommandContext) -> Option<String>,
}

/// Dispatch parameters passed to `try_handle_command`.
///
/// Groups all the caller-supplied context needed to dispatch and execute bot
/// commands.  Construct one per incoming message and pass it alongside the raw
/// message body.
pub struct CommandDispatch<'a> {
    /// The bot's display name (e.g., "Timmy").
    pub bot_name: &'a str,
    /// The bot's full Matrix user ID (e.g., `"@timmy:homeserver.local"`).
    pub bot_user_id: &'a str,
    /// Project root directory (needed by status, ambient).
    pub project_root: &'a Path,
    /// Agent pool (needed by status).
    pub agents: &'a AgentPool,
    /// Set of rooms with ambient mode enabled (needed by ambient).
    pub ambient_rooms: &'a Arc<Mutex<HashSet<OwnedRoomId>>>,
    /// The room this message came from (needed by ambient).
    pub room_id: &'a OwnedRoomId,
    /// Whether the message directly addressed the bot (mention/reply).
    /// Some commands (e.g. ambient) only operate when directly addressed.
    pub is_addressed: bool,
}

/// Context passed to individual command handlers.
pub struct CommandContext<'a> {
    /// The bot's display name (e.g., "Timmy").
    pub bot_name: &'a str,
    /// Any text after the command keyword, trimmed.
    pub args: &'a str,
    /// Project root directory (needed by status, ambient).
    pub project_root: &'a Path,
    /// Agent pool (needed by status).
    pub agents: &'a AgentPool,
    /// Set of rooms with ambient mode enabled (needed by ambient).
    pub ambient_rooms: &'a Arc<Mutex<HashSet<OwnedRoomId>>>,
    /// The room this message came from (needed by ambient).
    pub room_id: &'a OwnedRoomId,
    /// Whether the message directly addressed the bot (mention/reply).
    /// Some commands (e.g. ambient) only operate when directly addressed.
    pub is_addressed: bool,
}

/// Returns the full list of registered bot commands.
///
/// Add new commands here — they will automatically appear in `help` output.
pub fn commands() -> &'static [BotCommand] {
    &[
        BotCommand {
            name: "help",
            description: "Show this list of available commands",
            handler: handle_help,
        },
        BotCommand {
            name: "status",
            description: "Show pipeline status and agent availability",
            handler: handle_status,
        },
        BotCommand {
            name: "ambient",
            description: "Toggle ambient mode for this room: `ambient on` or `ambient off`",
            handler: handle_ambient,
        },
    ]
}

/// Try to match a user message against a registered bot command.
///
/// The message is expected to be the raw body text from Matrix (e.g.,
/// `"@timmy help"`). The bot mention prefix is stripped before matching.
///
/// Returns `Some(response)` if a command matched and was handled, `None`
/// otherwise (the caller should fall through to the LLM).
pub fn try_handle_command(dispatch: &CommandDispatch<'_>, message: &str) -> Option<String> {
    let command_text = strip_bot_mention(message, dispatch.bot_name, dispatch.bot_user_id);
    let trimmed = command_text.trim();
    if trimmed.is_empty() {
        return None;
    }

    let (cmd_name, args) = match trimmed.split_once(char::is_whitespace) {
        Some((c, a)) => (c, a.trim()),
        None => (trimmed, ""),
    };
    let cmd_lower = cmd_name.to_ascii_lowercase();

    let ctx = CommandContext {
        bot_name: dispatch.bot_name,
        args,
        project_root: dispatch.project_root,
        agents: dispatch.agents,
        ambient_rooms: dispatch.ambient_rooms,
        room_id: dispatch.room_id,
        is_addressed: dispatch.is_addressed,
    };

    commands()
        .iter()
        .find(|c| c.name == cmd_lower)
        .and_then(|c| (c.handler)(&ctx))
}

/// Strip the bot mention prefix from a raw message body.
///
/// Handles these forms (case-insensitive where applicable):
/// - `@bot_localpart:server.com rest` → `rest`
/// - `@bot_localpart rest` → `rest`
/// - `DisplayName rest` → `rest`
fn strip_bot_mention<'a>(message: &'a str, bot_name: &str, bot_user_id: &str) -> &'a str {
    let trimmed = message.trim();

    // Try full Matrix user ID (e.g. "@timmy:homeserver.local")
    if let Some(rest) = strip_prefix_ci(trimmed, bot_user_id) {
        return rest;
    }

    // Try @localpart (e.g. "@timmy")
    if let Some(localpart) = bot_user_id.split(':').next()
        && let Some(rest) = strip_prefix_ci(trimmed, localpart)
    {
        return rest;
    }

    // Try display name (e.g. "Timmy")
    if let Some(rest) = strip_prefix_ci(trimmed, bot_name) {
        return rest;
    }

    trimmed
}

/// Case-insensitive prefix strip that also requires the match to end at a
/// word boundary (whitespace, punctuation, or end-of-string).
fn strip_prefix_ci<'a>(text: &'a str, prefix: &str) -> Option<&'a str> {
    if text.len() < prefix.len() {
        return None;
    }
    if !text[..prefix.len()].eq_ignore_ascii_case(prefix) {
        return None;
    }
    let rest = &text[prefix.len()..];
    // Must be at end or followed by non-alphanumeric
    match rest.chars().next() {
        None => Some(rest), // exact match, empty remainder
        Some(c) if c.is_alphanumeric() || c == '-' || c == '_' => None, // not a word boundary
        _ => Some(rest),
    }
}

// ---------------------------------------------------------------------------
// Pipeline status helpers (moved from bot.rs)
// ---------------------------------------------------------------------------

/// Format a short display label for a work item.
///
/// Extracts the leading numeric ID from the file stem (e.g. `"293"` from
/// `"293_story_register_all_bot_commands"`) and combines it with the human-
/// readable name from the front matter when available.
///
/// Examples:
/// - `("293_story_foo", Some("Register all bot commands"))` → `"293 — Register all bot commands"`
/// - `("293_story_foo", None)` → `"293"`
/// - `("no_number_here", None)` → `"no_number_here"`
fn story_short_label(stem: &str, name: Option<&str>) -> String {
    let number = stem
        .split('_')
        .next()
        .filter(|s| !s.is_empty() && s.chars().all(|c| c.is_ascii_digit()))
        .unwrap_or(stem);
    match name {
        Some(n) => format!("{number} — {n}"),
        None => number.to_string(),
    }
}

/// Read all story IDs and names from a pipeline stage directory.
fn read_stage_items(
    project_root: &std::path::Path,
    stage_dir: &str,
) -> Vec<(String, Option<String>)> {
    let dir = project_root
        .join(".story_kit")
        .join("work")
        .join(stage_dir);
    if !dir.exists() {
        return Vec::new();
    }
    let mut items = Vec::new();
    if let Ok(entries) = std::fs::read_dir(&dir) {
        for entry in entries.flatten() {
            let path = entry.path();
            if path.extension().and_then(|e| e.to_str()) != Some("md") {
                continue;
            }
            if let Some(stem) = path.file_stem().and_then(|s| s.to_str()) {
                let name = std::fs::read_to_string(&path)
                    .ok()
                    .and_then(|contents| {
                        crate::io::story_metadata::parse_front_matter(&contents)
                            .ok()
                            .and_then(|m| m.name)
                    });
                items.push((stem.to_string(), name));
            }
        }
    }
    items.sort_by(|a, b| a.0.cmp(&b.0));
    items
}

/// Build the full pipeline status text formatted for Matrix (markdown).
pub fn build_pipeline_status(project_root: &std::path::Path, agents: &AgentPool) -> String {
    // Build a map from story_id → active AgentInfo for quick lookup.
    let active_agents = agents.list_agents().unwrap_or_default();
    let active_map: std::collections::HashMap<String, &crate::agents::AgentInfo> = active_agents
        .iter()
        .filter(|a| matches!(a.status, AgentStatus::Running | AgentStatus::Pending))
        .map(|a| (a.story_id.clone(), a))
        .collect();

    let config = ProjectConfig::load(project_root).ok();

    let mut out = String::from("**Pipeline Status**\n\n");

    let stages = [
        ("1_backlog", "Backlog"),
        ("2_current", "In Progress"),
        ("3_qa", "QA"),
        ("4_merge", "Merge"),
        ("5_done", "Done"),
    ];

    for (dir, label) in &stages {
        let items = read_stage_items(project_root, dir);
        let count = items.len();
        out.push_str(&format!("**{label}** ({count})\n"));
        if items.is_empty() {
            out.push_str("  *(none)*\n");
        } else {
            for (story_id, name) in &items {
                let display = story_short_label(story_id, name.as_deref());
                if let Some(agent) = active_map.get(story_id) {
                    let model_str = config
                        .as_ref()
                        .and_then(|cfg| cfg.find_agent(&agent.agent_name))
                        .and_then(|ac| ac.model.as_deref())
                        .unwrap_or("?");
                    out.push_str(&format!(
                        "  • {display} — {} ({model_str})\n",
                        agent.agent_name
                    ));
                } else {
                    out.push_str(&format!("  • {display}\n"));
                }
            }
        }
        out.push('\n');
    }

    // Free agents: configured agents not currently running or pending.
    out.push_str("**Free Agents**\n");
    if let Some(cfg) = &config {
        let busy_names: std::collections::HashSet<String> = active_agents
            .iter()
            .filter(|a| matches!(a.status, AgentStatus::Running | AgentStatus::Pending))
            .map(|a| a.agent_name.clone())
            .collect();

        let free: Vec<String> = cfg
            .agent
            .iter()
            .filter(|a| !busy_names.contains(&a.name))
            .map(|a| match &a.model {
                Some(m) => format!("{} ({})", a.name, m),
                None => a.name.clone(),
            })
            .collect();

        if free.is_empty() {
            out.push_str("  *(none — all agents busy)*\n");
        } else {
            for name in &free {
                out.push_str(&format!("  • {name}\n"));
            }
        }
    } else {
        out.push_str("  *(no agent config found)*\n");
    }

    out
}

// ---------------------------------------------------------------------------
// Built-in command handlers
// ---------------------------------------------------------------------------

fn handle_help(ctx: &CommandContext) -> Option<String> {
    let mut output = format!("**{} Commands**\n\n", ctx.bot_name);
    for cmd in commands() {
        output.push_str(&format!("- **{}** — {}\n", cmd.name, cmd.description));
    }
    Some(output)
}

fn handle_status(ctx: &CommandContext) -> Option<String> {
    Some(build_pipeline_status(ctx.project_root, ctx.agents))
}

/// Toggle ambient mode for this room.
///
/// Only acts when the message directly addressed the bot (`is_addressed=true`)
/// to prevent accidental toggling via ambient-mode traffic.
fn handle_ambient(ctx: &CommandContext) -> Option<String> {
    if !ctx.is_addressed {
        return None;
    }
    let enable = match ctx.args {
        "on" => true,
        "off" => false,
        _ => return Some("Usage: `ambient on` or `ambient off`".to_string()),
    };
    let room_ids: Vec<String> = {
        let mut ambient = ctx.ambient_rooms.lock().unwrap();
        if enable {
            ambient.insert(ctx.room_id.clone());
        } else {
            ambient.remove(ctx.room_id);
        }
        ambient.iter().map(|r| r.to_string()).collect()
    };
    save_ambient_rooms(ctx.project_root, &room_ids);
    let msg = if enable {
        "Ambient mode on. I'll respond to all messages in this room."
    } else {
        "Ambient mode off. I'll only respond when mentioned."
    };
    Some(msg.to_string())
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

#[cfg(test)]
mod tests {
    use super::*;
    use crate::agents::AgentPool;

    // -- test helpers -------------------------------------------------------

    fn make_room_id(s: &str) -> OwnedRoomId {
        s.parse().unwrap()
    }

    fn test_ambient_rooms() -> Arc<Mutex<HashSet<OwnedRoomId>>> {
        Arc::new(Mutex::new(HashSet::new()))
    }

    fn test_agents() -> Arc<AgentPool> {
        Arc::new(AgentPool::new_test(3000))
    }

    fn try_cmd(
        bot_name: &str,
        bot_user_id: &str,
        message: &str,
        ambient_rooms: &Arc<Mutex<HashSet<OwnedRoomId>>>,
        is_addressed: bool,
    ) -> Option<String> {
        let agents = test_agents();
        let room_id = make_room_id("!test:example.com");
        let dispatch = CommandDispatch {
            bot_name,
            bot_user_id,
            project_root: std::path::Path::new("/tmp"),
            agents: &agents,
            ambient_rooms,
            room_id: &room_id,
            is_addressed,
        };
        try_handle_command(&dispatch, message)
    }

    fn try_cmd_addressed(bot_name: &str, bot_user_id: &str, message: &str) -> Option<String> {
        try_cmd(bot_name, bot_user_id, message, &test_ambient_rooms(), true)
    }

    // -- strip_bot_mention --------------------------------------------------

    #[test]
    fn strip_mention_full_user_id() {
        let rest = strip_bot_mention(
            "@timmy:homeserver.local help",
            "Timmy",
            "@timmy:homeserver.local",
        );
        assert_eq!(rest.trim(), "help");
    }

    #[test]
    fn strip_mention_localpart() {
        let rest = strip_bot_mention("@timmy help me", "Timmy", "@timmy:homeserver.local");
        assert_eq!(rest.trim(), "help me");
    }

    #[test]
    fn strip_mention_display_name() {
        let rest = strip_bot_mention("Timmy help", "Timmy", "@timmy:homeserver.local");
        assert_eq!(rest.trim(), "help");
    }

    #[test]
    fn strip_mention_display_name_case_insensitive() {
        let rest = strip_bot_mention("timmy help", "Timmy", "@timmy:homeserver.local");
        assert_eq!(rest.trim(), "help");
    }

    #[test]
    fn strip_mention_no_match_returns_original() {
        let rest = strip_bot_mention("hello world", "Timmy", "@timmy:homeserver.local");
        assert_eq!(rest, "hello world");
    }

    #[test]
    fn strip_mention_does_not_match_longer_name() {
        // "@timmybot" should NOT match "@timmy"
        let rest = strip_bot_mention("@timmybot help", "Timmy", "@timmy:homeserver.local");
        assert_eq!(rest, "@timmybot help");
    }

    #[test]
    fn strip_mention_comma_after_name() {
        let rest = strip_bot_mention("@timmy, help", "Timmy", "@timmy:homeserver.local");
        assert_eq!(rest.trim().trim_start_matches(',').trim(), "help");
    }

    // -- try_handle_command -------------------------------------------------

    #[test]
    fn help_command_matches() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy help");
        assert!(result.is_some(), "help command should match");
    }

    #[test]
    fn help_command_case_insensitive() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy HELP");
        assert!(result.is_some(), "HELP should match case-insensitively");
    }

    #[test]
    fn unknown_command_returns_none() {
        let result = try_cmd_addressed(
            "Timmy",
            "@timmy:homeserver.local",
            "@timmy what is the weather?",
        );
        assert!(result.is_none(), "non-command should return None");
    }

    #[test]
    fn help_output_contains_all_commands() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy help");
        let output = result.unwrap();
        for cmd in commands() {
            assert!(
                output.contains(cmd.name),
                "help output must include command '{}'",
                cmd.name
            );
            assert!(
                output.contains(cmd.description),
                "help output must include description for '{}'",
                cmd.name
            );
        }
    }

    #[test]
    fn help_output_uses_bot_name() {
        let result = try_cmd_addressed("HAL", "@hal:example.com", "@hal help");
        let output = result.unwrap();
        assert!(
            output.contains("HAL Commands"),
            "help output should use bot name: {output}"
        );
    }

    #[test]
    fn help_output_formatted_as_markdown() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy help");
        let output = result.unwrap();
        assert!(
            output.contains("**help**"),
            "command name should be bold: {output}"
        );
        assert!(
            output.contains("- **"),
            "commands should be in a list: {output}"
        );
    }

    #[test]
    fn empty_message_after_mention_returns_none() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy");
        assert!(
            result.is_none(),
            "bare mention with no command should fall through to LLM"
        );
    }

    // -- status command -----------------------------------------------------

    #[test]
    fn status_command_matches() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy status");
        assert!(result.is_some(), "status command should match");
    }

    #[test]
    fn status_command_returns_pipeline_text() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy status");
        let output = result.unwrap();
        assert!(
            output.contains("Pipeline Status"),
            "status output should contain pipeline info: {output}"
        );
    }

    #[test]
    fn status_command_case_insensitive() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy STATUS");
        assert!(result.is_some(), "STATUS should match case-insensitively");
    }

    // -- ambient command ----------------------------------------------------

    #[test]
    fn ambient_on_requires_addressed() {
        let ambient_rooms = test_ambient_rooms();
        let room_id = make_room_id("!myroom:example.com");
        let result = try_cmd(
            "Timmy",
            "@timmy:homeserver.local",
            "@timmy ambient on",
            &ambient_rooms,
            false, // not addressed
        );
        // Should fall through to LLM when not addressed
        assert!(result.is_none(), "ambient should not fire in non-addressed mode");
        assert!(
            !ambient_rooms.lock().unwrap().contains(&room_id),
            "ambient_rooms should not be modified when not addressed"
        );
    }

    #[test]
    fn ambient_on_enables_ambient_mode() {
        let ambient_rooms = test_ambient_rooms();
        let agents = test_agents();
        let room_id = make_room_id("!myroom:example.com");
        let dispatch = CommandDispatch {
            bot_name: "Timmy",
            bot_user_id: "@timmy:homeserver.local",
            project_root: std::path::Path::new("/tmp"),
            agents: &agents,
            ambient_rooms: &ambient_rooms,
            room_id: &room_id,
            is_addressed: true,
        };
        let result = try_handle_command(&dispatch, "@timmy ambient on");
        assert!(result.is_some(), "ambient on should produce a response");
        let output = result.unwrap();
        assert!(
            output.contains("Ambient mode on"),
            "response should confirm ambient on: {output}"
        );
        assert!(
            ambient_rooms.lock().unwrap().contains(&room_id),
            "room should be in ambient_rooms after ambient on"
        );
    }

    #[test]
    fn ambient_off_disables_ambient_mode() {
        let ambient_rooms = test_ambient_rooms();
        let agents = test_agents();
        let room_id = make_room_id("!myroom:example.com");
        // Pre-insert the room
        ambient_rooms.lock().unwrap().insert(room_id.clone());

        let dispatch = CommandDispatch {
            bot_name: "Timmy",
            bot_user_id: "@timmy:homeserver.local",
            project_root: std::path::Path::new("/tmp"),
            agents: &agents,
            ambient_rooms: &ambient_rooms,
            room_id: &room_id,
            is_addressed: true,
        };
        let result = try_handle_command(&dispatch, "@timmy ambient off");
        assert!(result.is_some(), "ambient off should produce a response");
        let output = result.unwrap();
        assert!(
            output.contains("Ambient mode off"),
            "response should confirm ambient off: {output}"
        );
        assert!(
            !ambient_rooms.lock().unwrap().contains(&room_id),
            "room should be removed from ambient_rooms after ambient off"
        );
    }

    #[test]
    fn ambient_invalid_args_returns_usage() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy ambient");
        let output = result.unwrap();
        assert!(
            output.contains("Usage"),
            "invalid ambient args should show usage: {output}"
        );
    }

    // -- help lists status and ambient --------------------------------------

    #[test]
    fn help_output_includes_status() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy help");
        let output = result.unwrap();
        assert!(output.contains("status"), "help should list status command: {output}");
    }

    #[test]
    fn help_output_includes_ambient() {
        let result = try_cmd_addressed("Timmy", "@timmy:homeserver.local", "@timmy help");
        let output = result.unwrap();
        assert!(output.contains("ambient"), "help should list ambient command: {output}");
    }

    // -- strip_prefix_ci ----------------------------------------------------

    #[test]
    fn strip_prefix_ci_basic() {
        assert_eq!(strip_prefix_ci("Hello world", "hello"), Some(" world"));
    }

    #[test]
    fn strip_prefix_ci_no_match() {
        assert_eq!(strip_prefix_ci("goodbye", "hello"), None);
    }

    #[test]
    fn strip_prefix_ci_word_boundary_required() {
        assert_eq!(strip_prefix_ci("helloworld", "hello"), None);
    }

    #[test]
    fn strip_prefix_ci_exact_match() {
        assert_eq!(strip_prefix_ci("hello", "hello"), Some(""));
    }

    // -- story_short_label --------------------------------------------------

    #[test]
    fn short_label_extracts_number_and_name() {
        let label = story_short_label("293_story_register_all_bot_commands", Some("Register all bot commands"));
        assert_eq!(label, "293 — Register all bot commands");
    }

    #[test]
    fn short_label_number_only_when_no_name() {
        let label = story_short_label("297_story_improve_bot_status_command_formatting", None);
        assert_eq!(label, "297");
    }

    #[test]
    fn short_label_falls_back_to_stem_when_no_numeric_prefix() {
        let label = story_short_label("no_number_here", None);
        assert_eq!(label, "no_number_here");
    }

    #[test]
    fn short_label_does_not_include_underscore_slug() {
        let label = story_short_label("293_story_register_all_bot_commands_in_the_command_registry", Some("Register all bot commands"));
        assert!(
            !label.contains("story_register"),
            "label should not contain the slug portion: {label}"
        );
    }

    // -- build_pipeline_status formatting -----------------------------------

    #[test]
    fn status_does_not_show_full_filename_stem() {
        use std::io::Write;
        use tempfile::TempDir;

        let tmp = TempDir::new().unwrap();
        let stage_dir = tmp.path().join(".story_kit/work/2_current");
        std::fs::create_dir_all(&stage_dir).unwrap();

        // Write a story file with a front-matter name
        let story_path = stage_dir.join("293_story_register_all_bot_commands.md");
        let mut f = std::fs::File::create(&story_path).unwrap();
        writeln!(f, "---\nname: Register all bot commands\n---\n").unwrap();

        let agents = AgentPool::new_test(3000);
        let output = build_pipeline_status(tmp.path(), &agents);

        assert!(
            !output.contains("293_story_register_all_bot_commands"),
            "output must not show full filename stem: {output}"
        );
        assert!(
            output.contains("293 — Register all bot commands"),
            "output must show number and title: {output}"
        );
    }

    // -- commands registry --------------------------------------------------

    #[test]
    fn commands_registry_is_not_empty() {
        assert!(
            !commands().is_empty(),
            "command registry must contain at least one command"
        );
    }

    #[test]
    fn all_command_names_are_lowercase() {
        for cmd in commands() {
            assert_eq!(
                cmd.name,
                cmd.name.to_ascii_lowercase(),
                "command name '{}' must be lowercase",
                cmd.name
            );
        }
    }

    #[test]
    fn all_commands_have_descriptions() {
        for cmd in commands() {
            assert!(
                !cmd.description.is_empty(),
                "command '{}' must have a description",
                cmd.name
            );
        }
    }
}