//! doctor: environment checks — tools, config validity, paths,
//! permissions — with an optional --fix mode.

use crate::app::App;
use crate::runner::Runner;
use anyhow::{Context, Result};
use serde::Serialize;
use std::collections::BTreeMap;

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize)]
#[serde(rename_all = "lowercase")]
pub enum Status {
    Ok,
    Warn,
    Error,
}

#[derive(Debug, Clone, Serialize)]
pub struct Check {
    pub name: String,
    pub status: Status,
    pub detail: String,
}

pub struct DoctorReport {
    pub checks: Vec<Check>,
}

impl DoctorReport {
    pub fn ok(&self) -> bool {
        !self.checks.iter().any(|c| c.status == Status::Error)
    }

    pub fn problems(&self) -> usize {
        self.checks.iter().filter(|c| c.status != Status::Ok).count()
    }
}

/// Args for probing a tool's version.
fn probe_args(tool: &str) -> Vec<String> {
    match tool {
        "go" => vec!["version".to_string()],
        _ => vec!["--version".to_string()],
    }
}

pub fn run(app: &App, runner: &dyn Runner) -> DoctorReport {
    let mut checks = Vec::new();

    // --- tools ----------------------------------------------------------
    // (name, required)
    let tools: &[(&str, bool)] = &[
        ("git", true),
        ("sh", cfg!(unix)),
        ("curl", true),
        ("node", false),
        ("npm", false),
        ("python3", false),
        ("python", false),
        ("cargo", false),
        ("go", false),
        ("bun", false),
        ("uv", false),
        ("docker", false),
    ];
    let os = crate::toolchain::OsInfo::detect();
    for (tool, required) in tools {
        let found = if *tool == "python" {
            runner.which("python3").or_else(|| runner.which("python"))
        } else {
            runner.which(tool)
        };
        match found {
            Some(path) => {
                let mut detail = path.display().to_string();
                let empty = BTreeMap::new();
                if let Ok(out) = runner.run(tool, &probe_args(tool), &empty, None, true) {
                    if out.code == 0 {
                        let combined = format!("{}
{}", out.stdout, out.stderr);
                        if let Some(v) = crate::version::find_version(&combined) {
                            detail = format!("{} (v{v})", path.display());
                        }
                    }
                }
                checks.push(Check {
                    name: tool.to_string(),
                    status: Status::Ok,
                    detail,
                });
            }
            None => {
                let mut detail = if *required {
                    "required but not found on PATH".to_string()
                } else {
                    "not installed".to_string()
                };
                let cmds = crate::toolchain::install_commands(tool, &os);
                if !cmds.is_empty() {
                    detail.push_str(&format!(
                        " — on {}: {}",
                        os.name,
                        cmds.join(" | ")
                    ));
                }
                let status = if *required { Status::Error } else { Status::Ok };
                checks.push(Check {
                    name: tool.to_string(),
                    status,
                    detail,
                });
            }
        }
    }

    // --- configuration ---------------------------------------------------
    match &app.config_origin {
        Some(path) => checks.push(Check {
            name: "config".to_string(),
            status: Status::Ok,
            detail: path.display().to_string(),
        }),
        None => checks.push(Check {
            name: "config".to_string(),
            status: Status::Warn,
            detail: "no user config file found; using the embedded default catalog".to_string(),
        }),
    }
    let problems = crate::config::validate(&app.config);
    if problems.is_empty() {
        checks.push(Check {
            name: "config-schema".to_string(),
            status: Status::Ok,
            detail: format!("{} agents defined", app.catalog.len()),
        });
    } else {
        checks.push(Check {
            name: "config-schema".to_string(),
            status: Status::Error,
            detail: problems.join("; "),
        });
    }

    // --- state file ------------------------------------------------------
    match app.state.load() {
        Ok(sf) => checks.push(Check {
            name: "state".to_string(),
            status: Status::Ok,
            detail: format!("{} installed agent(s)", sf.installed.len()),
        }),
        Err(e) => checks.push(Check {
            name: "state".to_string(),
            status: Status::Error,
            detail: format!("{e:#}"),
        }),
    }

    // --- directories -----------------------------------------------------
    for (name, dir) in [
        ("install-dir", app.paths.install_dir.clone()),
        ("bin-dir", app.paths.bin_dir.clone()),
        ("log-dir", app.paths.log_dir.clone()),
    ] {
        let status = if dir.is_dir() {
            Status::Ok
        } else if app.paths.install_dir.parent().map(|p| p.is_dir()).unwrap_or(false) {
            Status::Warn
        } else {
            Status::Warn
        };
        let detail = if dir.is_dir() {
            dir.display().to_string()
        } else {
            format!("{} (missing; 'am doctor --fix' creates it)", dir.display())
        };
        checks.push(Check {
            name: name.to_string(),
            status,
            detail,
        });
    }

    // --- bin dir on PATH --------------------------------------------------
    let on_path = is_on_path(&app.paths.bin_dir);
    checks.push(Check {
        name: "bin-on-path".to_string(),
        status: if on_path { Status::Ok } else { Status::Warn },
        detail: if on_path {
            format!("{} is on PATH", app.paths.bin_dir.display())
        } else {
            format!(
                "{} is not on PATH — add it so agents are found from your shell",
                app.paths.bin_dir.display()
            )
        },
    });

    DoctorReport { checks }
}

fn is_on_path(dir: &std::path::Path) -> bool {
    let Some(path) = std::env::var_os("PATH") else {
        return false;
    };
    std::env::split_paths(&path).any(|p| {
        if cfg!(windows) {
            p.to_string_lossy().to_lowercase() == dir.to_string_lossy().to_lowercase()
        } else {
            p == dir
        }
    })
}

/// Offer to install the missing optional tools (node, python, ...) with
/// the command detected for the current OS. Returns what was repaired.
pub fn install_missing_tools(app: &App, runner: &dyn Runner) -> Result<Vec<String>> {
    let mut installed = Vec::new();
    let os = crate::toolchain::OsInfo::detect();
    for tool in ["git", "node", "python", "cargo", "go", "bun", "uv", "docker"] {
        if crate::toolchain::tool_is_present(tool, runner) {
            continue;
        }
        let cmds = crate::toolchain::install_commands(tool, &os);
        let Some(cmd) = cmds.first() else {
            continue;
        };
        if !app.confirm(&format!(
            "'{tool}' is missing — run the detected installer for {}? -> {cmd}",
            os.name
        ))? {
            continue;
        }
        let code = crate::toolchain::run_install_command(runner, cmd)?;
        crate::toolchain::refresh_path();
        installed.push(if code == 0 {
            format!("installed '{tool}' ({cmd})")
        } else {
            format!("failed to install '{tool}' (exit code {code})")
        });
    }
    Ok(installed)
}

/// Repair what can be repaired: create directories, fix a corrupt state file.
pub fn fix(app: &App) -> Result<Vec<String>> {
    let mut repaired = Vec::new();
    app.paths.ensure().context("creating directories")?;
    repaired.push(format!("created {}", app.paths.install_dir.display()));
    repaired.push(format!("created {}", app.paths.log_dir.display()));

    // Project cache: always refreshed (it derives from the journal).
    let cache = crate::projects::cache_file(app);
    if cache.exists() {
        std::fs::remove_file(&cache).ok();
        repaired.push(format!("project cache {} removed (rebuilt on next 'am projects')", cache.display()));
    }

    // Corrupt state file: back it up and start fresh.
    if app.state.path().exists() && app.state.load().is_err() {
        let backup = app
            .state
            .path()
            .with_extension("json.corrupt.bak");
        std::fs::rename(app.state.path(), &backup).with_context(|| {
            format!(
                "cannot back up corrupt state file {} to {}",
                app.state.path().display(),
                backup.display()
            )
        })?;
        app.state.save(&crate::state::StateFile::default())?;
        repaired.push(format!(
            "corrupt state file moved to {} and recreated empty",
            backup.display()
        ));
    }
    Ok(repaired)
}