use std::path::Path;
use std::process::Stdio;
use std::sync::Arc;
use std::time::Duration;

use async_trait::async_trait;
use serde_json::json;
use tokio::io::{AsyncRead, AsyncReadExt, BufReader};
use tokio::process::Command;
use tokio::sync::{Mutex, mpsc};
use tokio::time::{Instant, sleep_until};

use crate::platform::{ShellInfo, dangerous_command_patterns};
use crate::tools::traits::{Tool, ToolResult};
use crate::tools::{extract_u64, extract_bool, check_null_args};

const MAX_TIMEOUT_SECS: u64 = 600;
const MAX_OUTPUT_CHARS: usize = 50_000;
const PENDING_USER_ACTION_MARKER: &str = "__PICOBOT_PENDING_USER_ACTION__";
const USER_ACTION_HINT: &str =
    "该命令正在等待你完成外部操作。完成后请告诉我继续，或重新运行后续检查命令。";

/// Shell 类型枚举，支持跨平台
///
/// 这是 ShellInfo 的兼容包装，提供更方便的 API。
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ShellKind {
    Bash,
    PowerShell,
    Cmd,
}

impl ShellKind {
    /// 根据平台检测默认 shell
    pub fn detect() -> Self {
        let info = ShellInfo::default();
        match info.executable {
            "bash" => ShellKind::Bash,
            "powershell" => ShellKind::PowerShell,
            "cmd" => ShellKind::Cmd,
            _ => ShellKind::Bash, // fallback
        }
    }

    /// 从 ShellInfo 获取 ShellKind
    pub fn from_info(info: &ShellInfo) -> Self {
        match info.executable {
            "bash" => ShellKind::Bash,
            "powershell" => ShellKind::PowerShell,
            "cmd" => ShellKind::Cmd,
            _ => ShellKind::Bash,
        }
    }

    /// 获取对应的 ShellInfo
    pub fn to_info(&self) -> ShellInfo {
        match self {
            ShellKind::Bash => ShellInfo {
                name: "bash",
                executable: "bash",
                args: &["-c"],
            },
            ShellKind::PowerShell => ShellInfo {
                name: "shell",
                executable: "powershell",
                args: &["-Command"],
            },
            ShellKind::Cmd => ShellInfo {
                name: "shell",
                executable: "cmd",
                args: &["/C"],
            },
        }
    }

    /// Shell 可执行文件名
    pub fn executable(&self) -> &'static str {
        self.to_info().executable
    }

    /// 执行命令所需的参数
    pub fn command_args<'a>(&self, command: &'a str) -> Vec<&'a str> {
        let info = self.to_info();
        info.args.iter().map(|s| *s).chain(std::iter::once(command)).collect()
    }

    /// 工具名称
    pub fn tool_name(&self) -> &'static str {
        self.to_info().name
    }

    /// 工具描述
    pub fn tool_description(&self) -> &'static str {
        match self {
            ShellKind::Bash => "Execute a bash shell command and return its output. Use with caution.",
            ShellKind::PowerShell => "Execute a PowerShell command and return its output. Use with caution.",
            ShellKind::Cmd => "Execute a cmd shell command and return its output. Use with caution.",
        }
    }
}

pub struct BashTool {
    timeout_secs: u64,
    working_dir: Option<String>,
    deny_patterns: Vec<String>,
    shell: ShellKind,
}

impl BashTool {
    pub fn new() -> Self {
        Self {
            timeout_secs: 60,
            working_dir: None,
            deny_patterns: dangerous_command_patterns(),
            shell: ShellKind::detect(),
        }
    }

    pub fn with_timeout(mut self, timeout_secs: u64) -> Self {
        self.timeout_secs = timeout_secs;
        self
    }

    pub fn with_working_dir(mut self, dir: String) -> Self {
        self.working_dir = Some(dir);
        self
    }

    pub fn with_shell(mut self, shell: ShellKind) -> Self {
        self.shell = shell;
        self
    }

    fn guard_command(&self, command: &str) -> Option<String> {
        let lower = command.to_lowercase();
        for pattern in &self.deny_patterns {
            if regex::Regex::new(pattern)
                .ok()
                .map(|re| re.is_match(&lower))
                .unwrap_or(false)
            {
                return Some(format!(
                    "Command blocked by safety guard (dangerous pattern: {})",
                    pattern
                ));
            }
        }
        None
    }

    fn truncate_output(&self, output: &str) -> String {
        let char_count = output.chars().count();
        if char_count <= MAX_OUTPUT_CHARS {
            return output.to_string();
        }

        let half = MAX_OUTPUT_CHARS / 2;
        let head: String = output.chars().take(half).collect();
        let tail: String = output
            .chars()
            .skip(char_count.saturating_sub(half))
            .collect();
        format!(
            "{}...\n\n(... {} chars truncated ...)\n\n{}",
            head,
            char_count - MAX_OUTPUT_CHARS,
            tail
        )
    }

    fn pending_output(&self, output: &str) -> String {
        format!(
            "{}\n{}\n\n{}",
            PENDING_USER_ACTION_MARKER,
            USER_ACTION_HINT,
            self.truncate_output(output.trim())
        )
    }

    fn should_return_pending(&self, interactive: bool, output: &str) -> bool {
        let normalized = output.to_lowercase();
        let has_auth_phrase = [
            // 中文 — 原有
            "等待用户授权",
            "等待授权",
            "等待你授权",
            "在浏览器中打开以下链接进行认证",
            // 中文 — 新增（lark-cli 等工具的常见提示）
            "请在浏览器中",
            "请打开以下链接",
            "打开以下链接",
            "打开链接",
            "访问以下",
            "访问此链接",
            "复制链接",
            "输入验证码",
            "输入授权码",
            "完成认证",
            "完成授权",
            "请登录",
            "正在等待",
            "等待用户",
            "手动授权",
            // 英文 — 原有
            "open the following link",
            "waiting for authorization",
            "waiting for user authorization",
            "waiting for approval",
            "device/verify",
            "user_code=",
            // 英文 — 新增
            "visit the following url",
            "visit this url",
            "open the following url",
            "browser to authenticate",
            "browser to complete",
            "enter the code",
            "enter code",
            "verification code",
            "authorization code",
            "one-time code",
            "device code",
            "oauth",
            "go to the following",
            "navigate to the following",
            "paste the code",
        ]
        .iter()
        .any(|pattern| normalized.contains(pattern));

        has_auth_phrase || (interactive && !output.trim().is_empty())
    }
}

async fn drain_available_chunks(
    rx: &mut mpsc::UnboundedReceiver<(bool, String)>,
    stdout_buf: &Arc<Mutex<String>>,
    stderr_buf: &Arc<Mutex<String>>,
) {
    while let Ok((is_stderr, chunk)) = rx.try_recv() {
        if is_stderr {
            stderr_buf.lock().await.push_str(&chunk);
        } else {
            stdout_buf.lock().await.push_str(&chunk);
        }
    }
}

impl Default for BashTool {
    fn default() -> Self {
        Self::new()
    }
}

#[async_trait]
impl Tool for BashTool {
    fn name(&self) -> &str {
        self.shell.tool_name()
    }

    fn description(&self) -> &str {
        self.shell.tool_description()
    }

    fn parameters_schema(&self) -> serde_json::Value {
        json!({
            "type": "object",
            "properties": {
                "command": {
                    "type": "string",
                    "description": "The shell command to execute"
                },
                "timeout": {
                    "type": "integer",
                    "description": format!("Timeout in seconds (default {}, max {})", self.timeout_secs, MAX_TIMEOUT_SECS),
                    "minimum": 1,
                    "maximum": MAX_TIMEOUT_SECS
                },
                "interactive": {
                    "type": "boolean",
                    "description": "Whether this command may enter a wait-for-user-action flow such as browser/device authentication"
                }
            },
            "required": ["command"]
        })
    }

    fn exclusive(&self) -> bool {
        true // Shell commands should not run concurrently
    }

    async fn execute(&self, args: serde_json::Value) -> anyhow::Result<ToolResult> {
        if let Some(result) = check_null_args(&args, "bash") {
            return Ok(result);
        }

        let command = match args.get("command").and_then(|v| v.as_str()) {
            Some(c) => c,
            None => {
                return Ok(ToolResult {
                    success: false,
                    output: String::new(),
                    error: Some("Missing required parameter: command".to_string()),
                });
            }
        };

        // Safety check
        if let Some(error) = self.guard_command(command) {
            return Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some(error),
            });
        }

        let timeout_secs = extract_u64(&args, "timeout")
            .unwrap_or(self.timeout_secs)
            .min(MAX_TIMEOUT_SECS);
        let interactive = extract_bool(&args, "interactive").unwrap_or(false);

        let cwd = self
            .working_dir
            .as_ref()
            .map(|d| Path::new(d))
            .unwrap_or_else(|| Path::new("."));

        match self
            .run_command(command, cwd, timeout_secs, interactive)
            .await
        {
            Ok(output) => Ok(ToolResult {
                success: true,
                output,
                error: None,
            }),
            Err(e) => Ok(ToolResult {
                success: false,
                output: String::new(),
                error: Some(e),
            }),
        }
    }
}

impl BashTool {
    async fn run_command(
        &self,
        command: &str,
        cwd: &Path,
        timeout_secs: u64,
        interactive: bool,
    ) -> Result<String, String> {
        let mut cmd = Command::new(self.shell.executable());
        cmd.args(self.shell.command_args(command))
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .current_dir(cwd);

        let mut child = cmd.spawn().map_err(|e| format!("Failed to spawn: {}", e))?;

        let stdout = child.stdout.take();
        let stderr = child.stderr.take();
        let (tx, mut rx) = mpsc::unbounded_channel::<(bool, String)>();

        if let Some(stdout) = stdout {
            tokio::spawn(read_stream(stdout, false, tx.clone()));
        }
        if let Some(stderr) = stderr {
            tokio::spawn(read_stream(stderr, true, tx.clone()));
        }
        drop(tx);

        let stdout_buf = Arc::new(Mutex::new(String::new()));
        let stderr_buf = Arc::new(Mutex::new(String::new()));
        let deadline = Instant::now() + Duration::from_secs(timeout_secs);

        loop {
            tokio::select! {
                status = child.wait() => {
                    let status = status.map_err(|e| format!("Failed to wait: {}", e))?;
                    drain_available_chunks(&mut rx, &stdout_buf, &stderr_buf).await;
                    while let Some((is_stderr, chunk)) = rx.recv().await {
                        if is_stderr {
                            stderr_buf.lock().await.push_str(&chunk);
                        } else {
                            stdout_buf.lock().await.push_str(&chunk);
                        }
                    }
                    let output = format_command_output(&stdout_buf.lock().await, &stderr_buf.lock().await, Some(status.code().unwrap_or(-1)));
                    return Ok(self.truncate_output(&output));
                }
                Some((is_stderr, chunk)) = rx.recv() => {
                    if is_stderr {
                        stderr_buf.lock().await.push_str(&chunk);
                    } else {
                        stdout_buf.lock().await.push_str(&chunk);
                    }

                    let combined = format_command_output(&stdout_buf.lock().await, &stderr_buf.lock().await, None);
                    if self.should_return_pending(interactive, &combined) {
                        drain_available_chunks(&mut rx, &stdout_buf, &stderr_buf).await;
                        let _ = child.start_kill();
                        let _ = child.wait().await;
                        let combined = format_command_output(&stdout_buf.lock().await, &stderr_buf.lock().await, None);
                        return Ok(self.pending_output(&combined));
                    }
                }
                _ = tokio::time::sleep(Duration::from_secs(2)) => {
                    // Periodic safety net: when output has been silent for 2s,
                    // check OS-level process state to see if the child is
                    // genuinely blocked on stdin.  Also re-run keyword detection
                    // in case read_stream flushed a partial line since the last
                    // rx.recv() iteration.
                    if let Some(pid) = child.id() {
                        if crate::platform::is_process_waiting_on_stdin(pid) == Some(true) {
                            drain_available_chunks(&mut rx, &stdout_buf, &stderr_buf).await;
                            let combined = format_command_output(&stdout_buf.lock().await, &stderr_buf.lock().await, None);
                            if !combined.trim().is_empty() {
                                let _ = child.start_kill();
                                let _ = child.wait().await;
                                return Ok(self.pending_output(&combined));
                            }
                        }
                    }

                    let combined = format_command_output(&stdout_buf.lock().await, &stderr_buf.lock().await, None);
                    if self.should_return_pending(interactive, &combined) {
                        drain_available_chunks(&mut rx, &stdout_buf, &stderr_buf).await;
                        let combined = format_command_output(&stdout_buf.lock().await, &stderr_buf.lock().await, None);
                        let _ = child.start_kill();
                        let _ = child.wait().await;
                        return Ok(self.pending_output(&combined));
                    }
                }
                _ = sleep_until(deadline) => {
                    drain_available_chunks(&mut rx, &stdout_buf, &stderr_buf).await;
                    let combined = format_command_output(&stdout_buf.lock().await, &stderr_buf.lock().await, None);
                    let _ = child.start_kill();
                    let _ = child.wait().await;

                    // OS-level process state check: if the child was blocked on
                    // stdin, treat it as pending rather than a hard timeout error.
                    if let Some(pid) = child.id() {
                        if crate::platform::is_process_waiting_on_stdin(pid) == Some(true)
                            && !combined.trim().is_empty()
                        {
                            return Ok(self.pending_output(&combined));
                        }
                    }

                    if self.should_return_pending(interactive, &combined) {
                        return Ok(self.pending_output(&combined));
                    }
                    return Err(format!("Command timed out after {} seconds", timeout_secs));
                }
            }
        }
    }
}

/// Flush delay: if no new data arrives within this window, send any buffered
/// partial line immediately.  This ensures that prompts and URLs printed
/// without a trailing newline are still visible to the detection logic.
const STREAM_FLUSH_MS: u64 = 500;

async fn read_stream<R>(stream: R, is_stderr: bool, tx: mpsc::UnboundedSender<(bool, String)>)
where
    R: AsyncRead + Unpin + Send + 'static,
{
    let mut reader = BufReader::new(stream);
    let mut buffer = Vec::new();

    loop {
        let mut chunk = [0u8; 4096];

        tokio::select! {
            result = reader.read(&mut chunk) => {
                match result {
                    Ok(0) => break,
                    Ok(n) => {
                        buffer.extend_from_slice(&chunk[..n]);

                        // 发送完整行（逻辑不变）
                        while let Some(pos) = buffer.iter().position(|&b| b == b'\n') {
                            let line_bytes = &buffer[..pos + 1];
                            let line = decode_bytes(line_bytes);
                            let _ = tx.send((is_stderr, line));
                            buffer.drain(..pos + 1);
                        }
                    }
                    Err(_) => break,
                }
            }
            _ = tokio::time::sleep(Duration::from_millis(STREAM_FLUSH_MS)) => {
                // 超时未收到新数据：flush 不完整的行
                // 这确保像 lark-cli auth login 打印的 URL（不带换行符）
                // 也能被 run_command 的检测逻辑看到
                if !buffer.is_empty() {
                    let remainder = decode_bytes(&buffer);
                    let _ = tx.send((is_stderr, remainder));
                    buffer.clear();
                }
            }
        }
    }

    // 处理剩余的字节
    if !buffer.is_empty() {
        let remainder = decode_bytes(&buffer);
        let _ = tx.send((is_stderr, remainder));
    }
}

/// 尝试 UTF-8 解码，失败则尝试 GBK 解码
fn decode_bytes(bytes: &[u8]) -> String {
    // 首先尝试 UTF-8
    if let Ok(s) = std::str::from_utf8(bytes) {
        return s.to_string();
    }

    // 尝试 GBK 解码
    let (cow, _, had_errors) = encoding_rs::GBK.decode(bytes);
    if !had_errors {
        return cow.to_string();
    }

    // 如果 GBK 也失败，使用 lossy 转换
    String::from_utf8_lossy(bytes).to_string()
}

fn format_command_output(stdout: &str, stderr: &str, exit_code: Option<i32>) -> String {
    let mut output = String::new();

    if !stdout.is_empty() {
        output.push_str(stdout);
    }

    if !stderr.trim().is_empty() {
        if !output.is_empty() {
            output.push_str("\n");
        }
        output.push_str("STDERR:\n");
        output.push_str(stderr);
    }

    if let Some(code) = exit_code {
        output.push_str(&format!("\nExit code: {}", code));
    }

    output
}

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

    #[tokio::test]
    async fn test_simple_command() {
        let tool = BashTool::new();
        let command = if cfg!(target_os = "windows") {
            "Write-Output 'Hello World'"
        } else {
            "echo 'Hello World'"
        };
        let result = tool
            .execute(json!({ "command": command }))
            .await
            .unwrap();

        assert!(result.success);
        assert!(result.output.contains("Hello World"));
    }

    #[tokio::test]
    async fn test_pwd_command() {
        let tool = BashTool::new();
        let command = if cfg!(target_os = "windows") {
            "Get-Location"
        } else {
            "pwd"
        };
        let result = tool.execute(json!({ "command": command })).await.unwrap();

        assert!(result.success);
    }

    #[tokio::test]
    async fn test_ls_command() {
        let tool = BashTool::new();
        let temp_dir = std::env::temp_dir();
        let command = if cfg!(target_os = "windows") {
            format!("Get-ChildItem {}", temp_dir.display())
        } else {
            format!("ls -la {}", temp_dir.display())
        };
        let result = tool
            .execute(json!({ "command": command }))
            .await
            .unwrap();

        assert!(result.success);
    }

    #[tokio::test]
    async fn test_dangerous_rm() {
        let tool = BashTool::new();
        // 测试 Unix 危险命令模式
        let result = tool
            .execute(json!({ "command": "rm -rf /some/path" }))
            .await
            .unwrap();

        assert!(!result.success);
        assert!(result.error.unwrap().contains("blocked"));
    }

    #[tokio::test]
    async fn test_dangerous_windows_commands() {
        let tool = BashTool::new();
        // 测试 Windows del 命令模式（正则应该匹配）
        let result = tool
            .execute(json!({ "command": "del /f /q file.txt" }))
            .await
            .unwrap();

        assert!(!result.success);
        assert!(result.error.unwrap().contains("blocked"));
    }

    #[tokio::test]
    async fn test_dangerous_fork_bomb() {
        let tool = BashTool::new();
        let result = tool
            .execute(json!({ "command": ":(){ :|:& };:" }))
            .await
            .unwrap();

        assert!(!result.success);
        assert!(result.error.unwrap().contains("blocked"));
    }

    #[tokio::test]
    async fn test_missing_command() {
        let tool = BashTool::new();
        let result = tool.execute(json!({})).await.unwrap();

        assert!(!result.success);
        assert!(result.error.unwrap().contains("command"));
    }

    #[tokio::test]
    async fn test_timeout() {
        let tool = BashTool::new();
        let command = if cfg!(target_os = "windows") {
            "Start-Sleep -Seconds 10"
        } else {
            "sleep 10"
        };
        let result = tool
            .execute(json!({
                "command": command,
                "timeout": 1
            }))
            .await
            .unwrap();

        assert!(!result.success);
        assert!(result.error.unwrap().contains("timed out"));
    }

    #[tokio::test]
    async fn test_pending_user_action_detection() {
        let tool = BashTool::new();
        let command = if cfg!(target_os = "windows") {
            "Write-Host 'waiting for authorization'; Start-Sleep -Seconds 10"
        } else {
            "printf 'waiting for authorization'; sleep 10"
        };
        let result = tool
            .execute(json!({
                "command": command,
                "timeout": 5,
                "interactive": true
            }))
            .await
            .unwrap();

        assert!(result.success);
        assert!(result.output.contains(PENDING_USER_ACTION_MARKER));
    }

    #[test]
    fn test_truncate_output_handles_utf8_char_boundaries() {
        let tool = BashTool::new();
        let input = "全".repeat(MAX_OUTPUT_CHARS + 100);

        let output = tool.truncate_output(&input);

        assert!(output.contains("chars truncated"));
        assert!(output.is_char_boundary(output.len()));
    }

    #[test]
    fn test_shell_kind_detect() {
        let shell = ShellKind::detect();
        if cfg!(target_os = "windows") {
            assert_eq!(shell, ShellKind::PowerShell);
        } else {
            assert_eq!(shell, ShellKind::Bash);
        }
    }

    #[test]
    fn test_shell_kind_executable() {
        assert_eq!(ShellKind::Bash.executable(), "bash");
        assert_eq!(ShellKind::PowerShell.executable(), "powershell");
        assert_eq!(ShellKind::Cmd.executable(), "cmd");
    }

    #[test]
    fn test_shell_kind_command_args() {
        assert_eq!(ShellKind::Bash.command_args("echo hello"), vec!["-c" as &str, "echo hello"]);
        assert_eq!(ShellKind::PowerShell.command_args("echo hello"), vec!["-Command" as &str, "echo hello"]);
        assert_eq!(ShellKind::Cmd.command_args("echo hello"), vec!["/C" as &str, "echo hello"]);
    }
}