//! uninstall: stop the agent if needed, remove its files, bins and state
//! entry; --purge also removes logs and the user-config definition.
//! External agents (installed outside agent-manager) are removed through
//! their package manager when the catalog knows it, or by deleting the
//! executables found on PATH otherwise.

use super::*;
use crate::events::{Event, EventKind};
use anyhow::{Context, Result};
use std::path::PathBuf;
use std::process::Command as ProcessCommand;

pub fn run(app: &App, agent_name: &str, purge: bool) -> Result<i32> {
    let agent = require_agent(app, agent_name)?;
    let entry = app.state.get(&agent.name).ok().flatten();
    let Some(entry) = entry else {
        return uninstall_external(app, agent);
    };

    // Stop it first when running.
    if let Some(pid) = entry.pid {
        if crate::process::is_running(pid) {
            app.log.info(&format!("stopping running agent (pid {pid})"));
            if app.dry_run() {
                app.log.dry(format!("would stop pid {pid}"));
            } else {
                crate::process::stop_pid(pid, false, app.config.settings.stop_timeout());
                app.state.update_pid(&agent.name, None, None)?;
            }
        }
    }

    let dir = PathBuf::from(&entry.install_dir);
    if app.dry_run() {
        app.log.dry(format!("would remove {}", dir.display()));
    } else {
        if dir.exists() {
            std::fs::remove_dir_all(&dir)
                .with_context(|| format!("cannot remove {}", dir.display()))?;
        }
        for b in &entry.bins {
            let p = PathBuf::from(b);
            if p.is_file() {
                std::fs::remove_file(&p)
                    .with_context(|| format!("cannot remove {}", p.display()))?;
            }
        }
        app.state.remove(&agent.name)?;
    }

    if purge {
        let log = crate::process::agent_log_path(app, &agent.name);
        if app.dry_run() {
            app.log.dry(format!("would remove log {}", log.display()));
        } else if log.exists() {
            std::fs::remove_file(&log).ok();
        }
        remove_from_user_config(app, &agent.name)?;
    }

    app.emit(&Event::now(EventKind::Uninstall).with_agent(agent.name.clone()));
    app.log.success(&format!(
        "uninstalled {} (files removed{})",
        agent.title(),
        if purge { ", config purged" } else { "" }
    ));
    Ok(0)
}

/// Build the package-manager uninstall command for an external agent whose
/// install method is a known package manager and whose package is recorded.
fn package_plan(agent: &AgentDef) -> Option<Vec<String>> {
    use crate::config::InstallType;
    let spec = agent.install.as_ref()?;
    for m in spec.all_methods() {
        let Some(pkg) = m.package.as_deref() else {
            continue;
        };
        let plan = match m.kind {
            InstallType::Npm => {
                vec!["npm", "uninstall", "--global", pkg]
            }
            InstallType::Pip => {
                if which::which("pip").is_ok() {
                    vec!["pip", "uninstall", "-y", pkg]
                } else if which::which("python3").is_ok() {
                    vec!["python3", "-m", "pip", "uninstall", "-y", pkg]
                } else if which::which("python").is_ok() {
                    vec!["python", "-m", "pip", "uninstall", "-y", pkg]
                } else {
                    continue;
                }
            }
            InstallType::Uv => vec!["uv", "tool", "uninstall", pkg],
            InstallType::Cargo => vec!["cargo", "uninstall", pkg],
            InstallType::Bun => vec!["bun", "remove", "--global", pkg],
            _ => continue,
        };
        return Some(plan.into_iter().map(|s| s.to_string()).collect());
    }
    None
}

/// Best-effort removal of an agent installed outside agent-manager: first the
/// package-manager command when the catalog knows one, then the executable
/// files left on PATH (and their directory when it is dedicated to the
/// agent, e.g. AppData\Local\atomic-agent).
fn uninstall_external(app: &App, agent: &AgentDef) -> Result<i32> {
    let first_token = agent.first_token();

    // 1. Package-manager plan (npm, pip, uv, cargo, bun).
    if let Some(tokens) = package_plan(agent) {
        if which::which(&tokens[0]).is_ok() {
            app.log.info(&format!(
                "agent '{}' is external (installed outside agent-manager) — uninstall with: {}",
                agent.name,
                tokens.join(" ")
            ));
            if !app.confirm("Run this command?")? {
                app.log.info("cancelled — nothing was uninstalled");
                return Ok(0);
            }
            if app.dry_run() {
                app.log.dry(format!("would run: {}", tokens.join(" ")));
            } else {
                // resolve_program handles Windows .cmd/.bat shims (npm,
                // pip, ...) which std::process::Command cannot launch.
                let (prog, prefix) = crate::runner::resolve_program(&tokens[0]);
                let mut args = prefix;
                args.extend(tokens[1..].iter().cloned());
                let status = ProcessCommand::new(&prog)
                    .args(&args)
                    .status()
                    .with_context(|| format!("failed to run {}", tokens.join(" ")))?;
                if !status.success() {
                    app.log.warn("the command failed — removing the files it left behind");
                }
            }
        }
    }

    // 2. Whatever executable is still on PATH, delete it directly (and its
    // directory when it belongs to the agent).
    let still = first_token.as_deref().and_then(|t| which::which(t).ok());
    if let Some(path) = still {
        let parent = path.parent().map(|p| p.to_path_buf());
        let dedicated = parent
            .as_ref()
            .and_then(|p| p.file_name())
            .map(|n| n.to_string_lossy().eq_ignore_ascii_case(&agent.name))
            .unwrap_or(false);
        let target: PathBuf = if dedicated {
            parent.clone().unwrap_or_else(|| path.clone())
        } else {
            path.clone()
        };
        app.log.info(&format!(
            "remove leftover {} {}",
            if dedicated { "directory" } else { "file" },
            target.display()
        ));
        if !app.confirm("Delete it?")? {
            app.log.info(&format!("'{}' left in place", target.display()));
            return Ok(0);
        }
        if app.dry_run() {
            app.log.dry(format!("would remove {}", target.display()));
        } else if dedicated {
            std::fs::remove_dir_all(&target)
                .with_context(|| format!("cannot remove {}", target.display()))?;
        } else {
            std::fs::remove_file(&target)
                .with_context(|| format!("cannot remove {}", target.display()))?;
        }
    }

    // 3. Final verification.
    let gone = first_token
        .as_deref()
        .and_then(|t| which::which(t).ok())
        .is_none();
    if gone {
        app.emit(
            &Event::now(EventKind::Uninstall)
                .with_agent(agent.name.clone())
                .with_reason("external"),
        );
        app.log
            .success(&format!("uninstalled {} (external)", agent.title()));
    } else {
        app.log.warn(&format!(
            "{} is still present on PATH — remove it manually",
            agent.title()
        ));
    }
    Ok(0)
}

/// Remove the agent entry from the user config file (--purge).
fn remove_from_user_config(app: &App, name: &str) -> Result<()> {
    let Some(path) = &app.config_origin else {
        app.log.verbose("no user config file — nothing to purge");
        return Ok(());
    };
    let is_json = path.extension().map(|e| e == "json").unwrap_or(false);
    if is_json {
        app.log
            .warn("config purge is not supported for JSON config files");
        return Ok(());
    }
    let text = std::fs::read_to_string(path)
        .with_context(|| format!("cannot read {}", path.display()))?;
    let mut value: serde_yaml::Value = serde_yaml::from_str(&text)
        .with_context(|| format!("cannot parse {}", path.display()))?;
    let mut removed = false;
    if let serde_yaml::Value::Mapping(map) = &mut value {
        if let Some(serde_yaml::Value::Sequence(seq)) = map.get_mut("agents") {
            let before = seq.len();
            seq.retain(|v| {
                v.get("name")
                    .and_then(|n| n.as_str())
                    .map(|n| n != name)
                    .unwrap_or(true)
            });
            removed = seq.len() != before;
        }
    }
    if !removed {
        app.log.verbose(&format!("'{name}' not defined in {}", path.display()));
        return Ok(());
    }
    let backup = path.with_extension("yaml.bak");
    std::fs::copy(path, &backup)
        .with_context(|| format!("cannot create backup {}", backup.display()))?;
    std::fs::write(path, serde_yaml::to_string(&value)?)
        .with_context(|| format!("cannot write {}", path.display()))?;
    app.log.info(&format!(
        "removed '{name}' from {} (backup: {})",
        path.display(),
        backup.display()
    ));
    Ok(())
}

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

    fn agent_from_yaml(yaml: &str) -> AgentDef {
        #[derive(serde::Deserialize)]
        struct Wrap {
            agents: Vec<AgentDef>,
        }
        let w: Wrap = serde_yaml::from_str(yaml).unwrap();
        w.agents.into_iter().next().unwrap()
    }

    #[test]
    fn package_plan_npm() {
        let a = agent_from_yaml(
            r#"
agents:
  - name: x
    install:
      type: npm
      package: "@scope/pkg"
    run: x
"#,
        );
        let plan = package_plan(&a).unwrap();
        assert_eq!(plan, vec!["npm", "uninstall", "--global", "@scope/pkg"]);
    }

    #[test]
    fn package_plan_cargo() {
        let a = agent_from_yaml(
            r#"
agents:
  - name: x
    install:
      type: cargo
      package: my-crate
    run: x
"#,
        );
        let plan = package_plan(&a).unwrap();
        assert_eq!(plan, vec!["cargo", "uninstall", "my-crate"]);
    }

    #[test]
    fn package_plan_binary_is_none() {
        let a = agent_from_yaml(
            r#"
agents:
  - name: y
    install:
      type: binary
      repo: owner/repo
      binary: y
    run: y
"#,
        );
        assert!(package_plan(&a).is_none());
    }

    #[test]
    fn package_plan_unknown_method_is_none() {
        let a = agent_from_yaml(
            r#"
agents:
  - name: z
    install:
      type: git
      repo: https://example.com/z.git
    run: z
"#,
        );
        assert!(package_plan(&a).is_none());
    }
}