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

use async_trait::async_trait;
use serde_json::json;
use tokio::process::Command;
use tokio::time::timeout;

use crate::tools::traits::{Tool, ToolResult};

const MAX_TIMEOUT_SECS: u64 = 600;
const MAX_OUTPUT_CHARS: usize = 50_000;

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

impl BashTool {
    pub fn new() -> Self {
        Self {
            timeout_secs: 60,
            working_dir: None,
            deny_patterns: vec![
                r"\brm\s+-[rf]{1,2}\b".to_string(),
                r"\bdel\s+/[fq]\b".to_string(),
                r"\brmdir\s+/s\b".to_string(),
                r":\(\)\s*\{.*\};\s*:".to_string(),
            ],
        }
    }

    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
    }

    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 {
        if output.len() <= MAX_OUTPUT_CHARS {
            return output.to_string();
        }

        let half = MAX_OUTPUT_CHARS / 2;
        format!(
            "{}...\n\n(... {} chars truncated ...)\n\n{}",
            &output[..output.ceil_char_boundary(half)],
            output.len() - MAX_OUTPUT_CHARS,
            &output[output.floor_char_boundary(output.len() - half)..]
        )
    }
}

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

#[async_trait]
impl Tool for BashTool {
    fn name(&self) -> &str {
        "bash"
    }

    fn delegation_policy(&self) -> crate::tools::DelegationPolicy {
        crate::tools::DelegationPolicy::Delegatable
    }

    fn description(&self) -> &str {
        "Execute a bash shell command and return its output. Use with caution."
    }

    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
                }
            },
            "required": ["command"]
        })
    }

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

    async fn execute(&self, args: serde_json::Value) -> anyhow::Result<ToolResult> {
        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 = args
            .get("timeout")
            .and_then(|v| v.as_u64())
            .unwrap_or(self.timeout_secs)
            .min(MAX_TIMEOUT_SECS);

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

        match self.run_command(command, cwd, timeout_secs).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,
    ) -> Result<String, String> {
        let mut cmd = Command::new("bash");
        cmd.args(["-c", command])
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .current_dir(cwd)
            .kill_on_drop(true);

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

        let process_output =
            match timeout(Duration::from_secs(timeout_secs), child.wait_with_output()).await {
                Ok(Ok(output)) => output,
                Ok(Err(e)) => return Err(format!("Failed to wait: {}", e)),
                Err(_) => {
                    return Err(format!("Command timed out after {} seconds", timeout_secs));
                }
            };

        let mut output = String::new();

        if !process_output.stdout.is_empty() {
            let stdout_str = String::from_utf8_lossy(&process_output.stdout);
            output.push_str(&stdout_str);
        }

        if !process_output.stderr.is_empty() {
            let stderr_str = String::from_utf8_lossy(&process_output.stderr);
            if !stderr_str.trim().is_empty() {
                if !output.is_empty() {
                    output.push('\n');
                }
                output.push_str("STDERR:\n");
                output.push_str(&stderr_str);
            }
        }

        output.push_str(&format!(
            "\nExit code: {}",
            process_output.status.code().unwrap_or(-1)
        ));

        Ok(self.truncate_output(&output))
    }
}

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

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

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

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

        assert!(result.success);
    }

    #[tokio::test]
    async fn test_ls_command() {
        let tool = BashTool::new();
        let result = tool
            .execute(json!({ "command": "ls -la /tmp" }))
            .await
            .unwrap();

        assert!(result.success);
    }

    #[tokio::test]
    async fn test_dangerous_rm() {
        let tool = BashTool::new();
        let result = tool
            .execute(json!({ "command": "rm -rf /" }))
            .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 result = tool
            .execute(json!({
                "command": "sleep 10",
                "timeout": 1
            }))
            .await
            .unwrap();

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

    #[tokio::test]
    async fn test_large_stderr_does_not_deadlock() {
        let tool = BashTool::new().with_timeout(5);
        let result = tool
            .execute(json!({
                "command": "for i in $(seq 1 2000); do echo noisy-error-line >&2; done; echo done"
            }))
            .await
            .unwrap();

        assert!(result.success);
        assert!(result.output.contains("done"));
        assert!(result.output.contains("STDERR"));
    }
}