//! Command execution abstraction: real process execution for production,
//! an in-memory recorder for tests and dry runs.

use crate::output::Logger;
use anyhow::{Context, Result};
use std::collections::{BTreeMap, HashSet};
use std::path::{Path, PathBuf};

#[derive(Debug, Clone, Default)]
pub struct RunOutput {
    pub code: i32,
    pub stdout: String,
    pub stderr: String,
}

/// Resolve a command name to an executable path, handling Windows
/// .cmd/.bat scripts (which std::process::Command cannot launch directly).
/// Returns the program to spawn and a prefix of arguments to insert before
/// the caller's arguments (e.g. cmd.exe /C script.cmd).
pub fn resolve_program(cmd: &str) -> (String, Vec<String>) {
    #[cfg(windows)]
    {
        let path = if cmd.contains('\\') || cmd.contains('/') {
            Some(PathBuf::from(cmd))
        } else {
            which::which(cmd).ok()
        };
        if let Some(p) = path {
            let ext = p
                .extension()
                .and_then(|e| e.to_str())
                .unwrap_or("")
                .to_lowercase();
            if ext == "cmd" || ext == "bat" {
                let comspec = std::env::var("COMSPEC").unwrap_or_else(|_| "cmd.exe".to_string());
                return (comspec, vec!["/C".to_string(), p.display().to_string()]);
            }
            return (p.display().to_string(), Vec::new());
        }
    }
    (cmd.to_string(), Vec::new())
}

/// Execute external commands with logging and dry-run support.
pub trait Runner {
    fn run(
        &self,
        cmd: &str,
        args: &[String],
        env: &BTreeMap<String, String>,
        cwd: Option<&Path>,
        capture: bool,
    ) -> Result<RunOutput>;

    /// Locate a binary on the PATH (like the which command).
    fn which(&self, bin: &str) -> Option<PathBuf>;
}

/// Production runner backed by std::process::Command.
pub struct SystemRunner<'a> {
    pub dry_run: bool,
    pub verbose: bool,
    pub log: &'a Logger,
}

impl<'a> SystemRunner<'a> {
    pub fn new(dry_run: bool, verbose: bool, log: &'a Logger) -> Self {
        Self {
            dry_run,
            verbose,
            log,
        }
    }
}

impl<'a> Runner for SystemRunner<'a> {
    fn run(
        &self,
        cmd: &str,
        args: &[String],
        env: &BTreeMap<String, String>,
        cwd: Option<&Path>,
        capture: bool,
    ) -> Result<RunOutput> {
        let display = if args.is_empty() {
            cmd.to_string()
        } else {
            format!("{cmd} {}", args.join(" "))
        };
        if self.dry_run {
            self.log.dry(format!("would run: {display}"));
            return Ok(RunOutput::default());
        }
        self.log.cmd(&display);
        let (prog, prefix) = resolve_program(cmd);
        let mut full_args = prefix;
        full_args.extend(args.iter().cloned());
        let mut c = std::process::Command::new(&prog);
        c.args(&full_args);
        c.envs(env);
        if let Some(dir) = cwd {
            c.current_dir(dir);
        }
        if capture {
            let out = c
                .output()
                .with_context(|| format!("failed to execute: {display}"))?;
            let code = out.status.code().unwrap_or(-1);
            let stdout = String::from_utf8_lossy(&out.stdout).to_string();
            let stderr = String::from_utf8_lossy(&out.stderr).to_string();
            self.log.result(code, &stderr);
            Ok(RunOutput {
                code,
                stdout,
                stderr,
            })
        } else {
            let status = c
                .status()
                .with_context(|| format!("failed to execute: {display}"))?;
            Ok(RunOutput {
                code: status.code().unwrap_or(-1),
                stdout: String::new(),
                stderr: String::new(),
            })
        }
    }

    fn which(&self, bin: &str) -> Option<PathBuf> {
        which::which(bin).ok()
    }
}

/// In-memory runner for tests: records every invocation, returns success.
#[derive(Default)]
pub struct MockRunner {
    pub calls: std::sync::Mutex<Vec<String>>,
    pub found: HashSet<String>,
    pub outputs: std::sync::Mutex<Vec<RunOutput>>,
}

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

    pub fn with_found(mut self, bin: &str) -> Self {
        self.found.insert(bin.to_string());
        self
    }

    pub fn with_output(mut self, out: RunOutput) -> Self {
        self.outputs.get_mut().unwrap().push(out);
        self
    }

    pub fn snapshot(&self) -> Vec<String> {
        self.calls.lock().unwrap().clone()
    }
}

impl Runner for MockRunner {
    fn run(
        &self,
        cmd: &str,
        args: &[String],
        _env: &BTreeMap<String, String>,
        _cwd: Option<&Path>,
        _capture: bool,
    ) -> Result<RunOutput> {
        self.calls
            .lock()
            .unwrap()
            .push(format!("{cmd} {}", args.join(" ")));
        let out = self.outputs.lock().unwrap().pop();
        Ok(out.unwrap_or_default())
    }

    fn which(&self, bin: &str) -> Option<PathBuf> {
        if self.found.contains(bin) {
            Some(PathBuf::from(bin))
        } else {
            None
        }
    }
}