use std::time::{Duration, SystemTime, UNIX_EPOCH};

use serde::Serialize;

use crate::api::client::{ApiClient, ApiClientError};
use crate::api::schema::{
    AgentStatus, Method, OutputMatch, PaneAgentState, PaneWaitForOutputParams, ReadFormat,
    ReadSource, Request, SplitDirection, Subscription,
};

mod agent;
mod integration;
mod pane;
mod server;
mod status;
mod tab;
mod workspace;

pub enum CommandOutcome {
    Handled(i32),
    NotCli,
}

pub fn maybe_run(args: &[String]) -> std::io::Result<CommandOutcome> {
    let Some(command) = args.get(1).map(|arg| arg.as_str()) else {
        return Ok(CommandOutcome::NotCli);
    };

    let exit_code = match command {
        "server" => {
            let Some(exit_code) = server::run_server_command(&args[2..])? else {
                return Ok(CommandOutcome::NotCli);
            };
            exit_code
        }
        "status" => status::run_status_command(&args[2..])?,
        "config" => run_config_command(&args[2..])?,
        "workspace" => workspace::run_workspace_command(&args[2..])?,
        "tab" => tab::run_tab_command(&args[2..])?,
        "agent" => agent::run_agent_command(&args[2..])?,
        "terminal" => run_terminal_command(&args[2..])?,
        "pane" => pane::run_pane_command(&args[2..])?,
        "wait" => run_wait_command(&args[2..])?,
        "integration" => integration::run_integration_command(&args[2..])?,
        "session" => run_session_command(&args[2..])?,
        _ => return Ok(CommandOutcome::NotCli),
    };

    Ok(CommandOutcome::Handled(exit_code))
}

fn run_config_command(args: &[String]) -> std::io::Result<i32> {
    let Some(subcommand) = args.first().map(|arg| arg.as_str()) else {
        print_config_help();
        return Ok(2);
    };

    match subcommand {
        "reset-keys" => config_reset_keys(&args[1..]),
        "help" | "--help" | "-h" => {
            print_config_help();
            Ok(0)
        }
        _ => {
            print_config_help();
            Ok(2)
        }
    }
}

fn config_reset_keys(args: &[String]) -> std::io::Result<i32> {
    if !args.is_empty() {
        eprintln!("usage: herdr config reset-keys");
        return Ok(2);
    }

    let path = crate::config::config_path();
    if !path.exists() {
        println!(
            "No config file found at {}. Built-in v2 keybindings already apply.",
            path.display()
        );
        return Ok(0);
    }

    let content = std::fs::read_to_string(&path)?;
    let parsed = match content.parse::<toml::Value>() {
        Ok(value) => value,
        Err(err) => {
            eprintln!(
                "config file at {} is invalid TOML: {err}. Fix it manually or move it aside to use defaults.",
                path.display()
            );
            return Ok(1);
        }
    };
    let Some(table) = parsed.as_table() else {
        eprintln!(
            "config file at {} is invalid TOML: top-level config must be a table.",
            path.display()
        );
        return Ok(1);
    };

    if !table.contains_key("keys") {
        println!(
            "No [keys] config found in {}. Built-in v2 keybindings already apply.",
            path.display()
        );
        return Ok(0);
    }

    let (updated, removed) = crate::config::remove_keybinding_config_sections(&content);
    if !removed {
        eprintln!(
            "could not safely remove keybinding config from {} without rewriting comments; edit the file manually or remove the top-level keys setting.",
            path.display()
        );
        return Ok(1);
    }
    if let Err(err) = updated.parse::<toml::Value>() {
        eprintln!(
            "removing keybinding config would make {} invalid TOML: {err}; leaving config unchanged",
            path.display()
        );
        return Ok(1);
    }

    let backup_path = key_config_backup_path(&path);
    std::fs::copy(&path, &backup_path)?;
    std::fs::write(&path, updated)?;

    println!("Created backup: {}", backup_path.display());
    println!(
        "Removed [keys], [keys.indexed], and [[keys.command]] from {}.",
        path.display()
    );
    println!("Built-in v2 keybindings will apply after Herdr restarts or reloads config.");
    println!("If a Herdr server is running, run `herdr server reload-config` to apply this now.");
    println!(
        "To restore: cp {} {}",
        backup_path.display(),
        path.display()
    );
    Ok(0)
}

fn key_config_backup_path(path: &std::path::Path) -> std::path::PathBuf {
    let timestamp = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .map(|duration| duration.as_secs())
        .unwrap_or(0);
    let file_name = path
        .file_name()
        .and_then(|name| name.to_str())
        .unwrap_or("config.toml");
    path.with_file_name(format!("{file_name}.bak-keybind-v2-{timestamp}"))
}

fn run_terminal_command(args: &[String]) -> std::io::Result<i32> {
    let Some(subcommand) = args.first().map(|arg| arg.as_str()) else {
        print_terminal_help();
        return Ok(2);
    };

    match subcommand {
        "attach" => terminal_attach(&args[1..]),
        "help" | "--help" | "-h" => {
            print_terminal_help();
            Ok(0)
        }
        _ => {
            print_terminal_help();
            Ok(2)
        }
    }
}

fn run_wait_command(args: &[String]) -> std::io::Result<i32> {
    let Some(subcommand) = args.first().map(|arg| arg.as_str()) else {
        print_wait_help();
        return Ok(2);
    };

    match subcommand {
        "output" => wait_output(&args[1..]),
        "agent-status" => wait_agent_status(&args[1..]),
        "help" | "--help" | "-h" => {
            print_wait_help();
            Ok(0)
        }
        _ => {
            print_wait_help();
            Ok(2)
        }
    }
}

fn run_session_command(args: &[String]) -> std::io::Result<i32> {
    let Some(subcommand) = args.first().map(|arg| arg.as_str()) else {
        print_session_help();
        return Ok(2);
    };

    match subcommand {
        "list" => session_list(&args[1..]),
        "attach" => session_attach_help(&args[1..]),
        "stop" => session_stop(&args[1..]),
        "delete" => session_delete(&args[1..]),
        "help" | "--help" | "-h" => {
            print_session_help();
            Ok(0)
        }
        _ => {
            print_session_help();
            Ok(2)
        }
    }
}

fn session_attach_help(args: &[String]) -> std::io::Result<i32> {
    if matches!(
        args.first().map(String::as_str),
        Some("help" | "--help" | "-h")
    ) {
        eprintln!("usage: herdr session attach <name>");
        return Ok(0);
    }
    eprintln!("usage: herdr session attach <name>");
    Ok(2)
}

fn session_list(args: &[String]) -> std::io::Result<i32> {
    let json = match parse_session_json_only(args, "usage: herdr session list [--json]") {
        Ok(json) => json,
        Err(code) => return Ok(code),
    };

    let sessions = crate::session::list_sessions()?;
    if json {
        _print_json(&serde_json::json!({
            "sessions": sessions,
        }));
    } else {
        print_session_table(&sessions);
    }
    Ok(0)
}

fn session_stop(args: &[String]) -> std::io::Result<i32> {
    let (name, json) =
        match parse_session_name_and_json(args, "usage: herdr session stop <name> [--json]") {
            Ok(parsed) => parsed,
            Err(code) => return Ok(code),
        };

    let target = match crate::session::parse_target_name(&name) {
        Ok(target) => target,
        Err(message) => {
            print_session_error("invalid_session_name", &message);
            return Ok(1);
        }
    };
    match crate::session::stop_session(target.as_deref()) {
        Ok(session) => {
            if json {
                _print_json(&serde_json::json!({
                    "stopped": true,
                    "session": session,
                }));
            } else {
                println!("stopped session {}", session.name);
            }
            Ok(0)
        }
        Err(message) => {
            print_session_error("session_stop_failed", &message);
            Ok(1)
        }
    }
}

fn session_delete(args: &[String]) -> std::io::Result<i32> {
    let (name, json) =
        match parse_session_name_and_json(args, "usage: herdr session delete <name> [--json]") {
            Ok(parsed) => parsed,
            Err(code) => return Ok(code),
        };

    match crate::session::delete_session(&name) {
        Ok(session) => {
            if json {
                _print_json(&serde_json::json!({
                    "deleted": true,
                    "session": session,
                }));
            } else {
                println!("deleted session {}", session.name);
            }
            Ok(0)
        }
        Err(message) => {
            print_session_error("session_delete_failed", &message);
            Ok(1)
        }
    }
}

fn terminal_attach(args: &[String]) -> std::io::Result<i32> {
    let (terminal_id, takeover) = match parse_attach_target(
        args,
        "usage: herdr terminal attach <terminal_id> [--takeover]",
    ) {
        Ok(parsed) => parsed,
        Err(code) => return Ok(code),
    };
    crate::client::run_terminal_attach(terminal_id, takeover)?;
    Ok(0)
}

pub(super) fn parse_attach_target(args: &[String], usage: &str) -> Result<(String, bool), i32> {
    let Some(target) = args.first() else {
        eprintln!("{usage}");
        return Err(2);
    };
    let mut takeover = false;
    for arg in &args[1..] {
        match arg.as_str() {
            "--takeover" => takeover = true,
            "help" | "--help" | "-h" => {
                eprintln!("{usage}");
                return Err(0);
            }
            other => {
                eprintln!("unknown option: {other}");
                return Err(2);
            }
        }
    }
    Ok((target.clone(), takeover))
}

fn wait_output(args: &[String]) -> std::io::Result<i32> {
    let Some(raw_pane_id) = args.first() else {
        eprintln!("usage: herdr wait output <pane_id> --match <text> [--source visible|recent|recent-unwrapped] [--lines N] [--timeout MS] [--regex]");
        return Ok(2);
    };

    let pane_id = normalize_pane_id(raw_pane_id);
    let mut source = ReadSource::Recent;
    let mut lines = None;
    let mut timeout_ms = None;
    let mut strip_ansi = true;
    let mut regex = false;
    let mut match_value = None;

    let mut index = 1;
    while index < args.len() {
        match args[index].as_str() {
            "--match" => {
                let Some(value) = args.get(index + 1) else {
                    eprintln!("missing value for --match");
                    return Ok(2);
                };
                match_value = Some(value.clone());
                index += 2;
            }
            "--source" => {
                let Some(value) = args.get(index + 1) else {
                    eprintln!("missing value for --source");
                    return Ok(2);
                };
                source = parse_read_source(value)?;
                index += 2;
            }
            "--lines" => {
                let Some(value) = args.get(index + 1) else {
                    eprintln!("missing value for --lines");
                    return Ok(2);
                };
                lines = Some(parse_u32_flag("--lines", value)?);
                index += 2;
            }
            "--timeout" => {
                let Some(value) = args.get(index + 1) else {
                    eprintln!("missing value for --timeout");
                    return Ok(2);
                };
                timeout_ms = Some(parse_u64_flag("--timeout", value)?);
                index += 2;
            }
            "--regex" => {
                regex = true;
                index += 1;
            }
            "--raw" => {
                strip_ansi = false;
                index += 1;
            }
            other => {
                eprintln!("unknown option: {other}");
                return Ok(2);
            }
        }
    }

    let Some(match_value) = match_value else {
        eprintln!("missing required --match");
        return Ok(2);
    };

    let matcher = if regex {
        OutputMatch::Regex { value: match_value }
    } else {
        OutputMatch::Substring { value: match_value }
    };

    let response = send_request(&Request {
        id: "cli:wait:output".into(),
        method: Method::PaneWaitForOutput(PaneWaitForOutputParams {
            pane_id,
            source,
            lines,
            r#match: matcher,
            timeout_ms,
            strip_ansi,
        }),
    })?;

    if response.get("error").is_some() {
        eprintln!("{}", serde_json::to_string(&response).unwrap());
        return Ok(1);
    }

    println!("{}", serde_json::to_string(&response).unwrap());
    Ok(0)
}

fn wait_agent_status(args: &[String]) -> std::io::Result<i32> {
    let Some(raw_pane_id) = args.first() else {
        eprintln!("usage: herdr wait agent-status <pane_id> --status <idle|working|blocked|done|unknown> [--timeout MS]");
        return Ok(2);
    };

    let pane_id = normalize_pane_id(raw_pane_id);
    let mut timeout_ms = None;
    let mut desired_status = None;

    let mut index = 1;
    while index < args.len() {
        match args[index].as_str() {
            "--status" => {
                let Some(value) = args.get(index + 1) else {
                    eprintln!("missing value for --status");
                    return Ok(2);
                };
                desired_status = Some(parse_agent_status(value)?);
                index += 2;
            }
            "--timeout" => {
                let Some(value) = args.get(index + 1) else {
                    eprintln!("missing value for --timeout");
                    return Ok(2);
                };
                timeout_ms = Some(parse_u64_flag("--timeout", value)?);
                index += 2;
            }
            other => {
                eprintln!("unknown option: {other}");
                return Ok(2);
            }
        }
    }

    let Some(agent_status) = desired_status else {
        eprintln!("missing required --status");
        return Ok(2);
    };

    wait_for_agent_change(
        Request {
            id: "cli:wait:agent-status".into(),
            method: Method::EventsSubscribe(crate::api::schema::EventsSubscribeParams {
                subscriptions: vec![Subscription::PaneAgentStatusChanged {
                    pane_id,
                    agent_status: Some(agent_status),
                }],
            }),
        },
        timeout_ms,
        "timed out waiting for agent status change",
    )
}

pub(super) fn wait_for_agent_change(
    request: Request,
    timeout_ms: Option<u64>,
    timeout_message: &str,
) -> std::io::Result<i32> {
    let read_timeout = timeout_ms.map(Duration::from_millis);
    let (ack, mut stream) = ApiClient::local()
        .subscribe_value(&request, read_timeout)
        .map_err(api_client_error_to_io)?;
    if let Err(err) = crate::api::client::parse_response_value(ack) {
        if let ApiClientError::ErrorResponse(response) = err {
            eprintln!("{}", serde_json::to_string(&response).unwrap());
            return Ok(1);
        }
        return Err(api_client_error_to_io(err));
    }

    match stream.next_event() {
        Ok(None) => {
            eprintln!("subscription closed before event arrived");
            Ok(1)
        }
        Ok(Some(event_value)) => {
            println!("{}", serde_json::to_string(&event_value).unwrap());
            Ok(0)
        }
        Err(ApiClientError::Io(err)) if api_timeout_error(&err) => {
            eprintln!("{timeout_message}");
            Ok(1)
        }
        Err(err) => Err(api_client_error_to_io(err)),
    }
}

pub(super) fn print_response(response: &serde_json::Value) -> std::io::Result<i32> {
    if response.get("error").is_some() {
        eprintln!("{}", serde_json::to_string(response).unwrap());
        return Ok(1);
    }

    println!("{}", serde_json::to_string(response).unwrap());
    Ok(0)
}

pub(super) fn send_ok_request(method: Method) -> std::io::Result<i32> {
    let response = send_request(&Request {
        id: "cli:request".into(),
        method,
    })?;

    if response.get("error").is_some() {
        eprintln!("{}", serde_json::to_string(&response).unwrap());
        return Ok(1);
    }

    Ok(0)
}

pub(super) fn send_request(request: &Request) -> std::io::Result<serde_json::Value> {
    ApiClient::local()
        .request_value(request)
        .map_err(api_client_error_to_io)
}

fn api_timeout_error(err: &std::io::Error) -> bool {
    matches!(
        err.kind(),
        std::io::ErrorKind::TimedOut | std::io::ErrorKind::WouldBlock
    )
}

fn api_client_error_to_io(err: ApiClientError) -> std::io::Error {
    match err {
        ApiClientError::Io(err) => err,
        err => std::io::Error::other(err),
    }
}

pub(super) fn normalize_workspace_id(value: &str) -> String {
    value.to_string()
}

pub(super) fn normalize_tab_id(value: &str) -> String {
    value.to_string()
}

pub(super) fn normalize_pane_id(value: &str) -> String {
    value.to_string()
}

pub(super) fn parse_split_direction(value: &str) -> std::io::Result<SplitDirection> {
    match value {
        "right" => Ok(SplitDirection::Right),
        "down" => Ok(SplitDirection::Down),
        _ => Err(std::io::Error::other(format!(
            "invalid split direction: {value}"
        ))),
    }
}

pub(super) fn parse_read_source(value: &str) -> std::io::Result<ReadSource> {
    match value {
        "visible" => Ok(ReadSource::Visible),
        "recent" => Ok(ReadSource::Recent),
        "recent-unwrapped" | "recent_unwrapped" => Ok(ReadSource::RecentUnwrapped),
        _ => Err(std::io::Error::other(format!(
            "invalid read source: {value}"
        ))),
    }
}

pub(super) fn parse_read_format(value: &str) -> std::io::Result<ReadFormat> {
    match value {
        "text" => Ok(ReadFormat::Text),
        "ansi" => Ok(ReadFormat::Ansi),
        _ => Err(std::io::Error::other(format!(
            "invalid read format: {value}"
        ))),
    }
}

fn parse_agent_status(value: &str) -> std::io::Result<AgentStatus> {
    match value {
        "idle" => Ok(AgentStatus::Idle),
        "working" => Ok(AgentStatus::Working),
        "blocked" => Ok(AgentStatus::Blocked),
        "done" => Ok(AgentStatus::Done),
        "unknown" => Ok(AgentStatus::Unknown),
        _ => Err(std::io::Error::other(format!(
            "invalid agent status: {value} (expected idle, working, blocked, done, or unknown)"
        ))),
    }
}

pub(super) fn parse_pane_agent_state(value: &str) -> std::io::Result<PaneAgentState> {
    match value {
        "idle" => Ok(PaneAgentState::Idle),
        "working" => Ok(PaneAgentState::Working),
        "blocked" => Ok(PaneAgentState::Blocked),
        "unknown" => Ok(PaneAgentState::Unknown),
        _ => Err(std::io::Error::other(format!(
            "invalid pane agent state: {value} (expected idle, working, blocked, or unknown)"
        ))),
    }
}

pub(super) fn parse_u32_flag(flag: &str, value: &str) -> std::io::Result<u32> {
    value
        .parse::<u32>()
        .map_err(|_| std::io::Error::other(format!("invalid value for {flag}: {value}")))
}

pub(super) fn parse_u64_flag(flag: &str, value: &str) -> std::io::Result<u64> {
    value
        .parse::<u64>()
        .map_err(|_| std::io::Error::other(format!("invalid value for {flag}: {value}")))
}

fn parse_session_json_only(args: &[String], usage: &str) -> Result<bool, i32> {
    match args {
        [] => Ok(false),
        [flag] if flag == "--json" => Ok(true),
        _ => {
            eprintln!("{usage}");
            Err(2)
        }
    }
}

fn parse_session_name_and_json(args: &[String], usage: &str) -> Result<(String, bool), i32> {
    let mut name = None;
    let mut json = false;
    for arg in args {
        if arg == "--json" {
            json = true;
        } else if name.is_none() {
            name = Some(arg.clone());
        } else {
            eprintln!("{usage}");
            return Err(2);
        }
    }

    let Some(name) = name else {
        eprintln!("{usage}");
        return Err(2);
    };
    Ok((name, json))
}

fn print_session_table(sessions: &[crate::session::SessionInfo]) {
    println!("{:<20} {:<8} {:<48} socket", "name", "status", "directory");
    for session in sessions {
        println!(
            "{:<20} {:<8} {:<48} {}",
            session.name,
            if session.running {
                "running"
            } else {
                "stopped"
            },
            session.session_dir,
            session.socket_path
        );
    }
}

fn print_session_error(code: &str, message: &str) {
    eprintln!(
        "{}",
        serde_json::to_string(&serde_json::json!({
            "error": {
                "code": code,
                "message": message,
            }
        }))
        .unwrap()
    );
}

fn print_config_help() {
    eprintln!("herdr config commands:");
    eprintln!("  herdr config reset-keys  back up config.toml and remove custom keybindings");
}

fn print_terminal_help() {
    eprintln!("herdr terminal commands:");
    eprintln!("  herdr terminal attach <terminal_id> [--takeover]");
    eprintln!("  detach from direct attach with ctrl+b q; send literal ctrl+b with ctrl+b ctrl+b");
}

fn print_wait_help() {
    eprintln!("herdr wait commands:");
    eprintln!("  herdr wait output <pane_id> --match <text> [--source visible|recent|recent-unwrapped] [--lines N] [--timeout MS] [--regex] [--raw]");
    eprintln!(
        "  herdr wait agent-status <pane_id> --status <idle|working|blocked|done|unknown> [--timeout MS]"
    );
}

fn print_session_help() {
    eprintln!("herdr session commands:");
    eprintln!("  herdr session list [--json]");
    eprintln!("  herdr session attach <name>");
    eprintln!("  herdr session stop <name> [--json]");
    eprintln!("  herdr session delete <name> [--json]");
    eprintln!("  use 'default' as <name> to target the default session for stop");
}

fn _print_json<T: Serialize>(value: &T) {
    println!("{}", serde_json::to_string(value).unwrap());
}