//! Per-user git credentials and commit identity.
//!
//! Stored in the database and rendered into the user's home directory
//! (`/data/users/<name>/home`), which is the home of their sandboxed agents,
//! terminals and git client: `.git-credentials` (credential store) and
//! `.gitconfig-codecraft`, included from `.gitconfig` so the user's own git
//! configuration stays untouched.

use crate::app::App;
use crate::store::User;
use anyhow::Result;
use serde::{Deserialize, Serialize};
use std::path::PathBuf;

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct GitCredential {
    /// Host, optionally with a path prefix (e.g. "git.example.com" or "github.com/org").
    pub host: String,
    pub username: String,
    /// Password or API token. Empty in updates = keep the stored one.
    #[serde(default)]
    pub token: String,
    /// "https" (default) or "http".
    #[serde(default)]
    pub protocol: String,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct GitSettings {
    #[serde(default)]
    pub name: String,
    #[serde(default)]
    pub email: String,
    #[serde(default)]
    pub credentials: Vec<GitCredential>,
}

/// The user's commit identity as environment variables. They take precedence over a
/// repository's own `user.name`/`user.email`, so commits made by agents, terminals and
/// the git panel always carry the identity from the settings.
pub fn identity_env(app: &App, user_id: &str) -> Vec<(String, String)> {
    let s: GitSettings = app.store.user_setting(user_id, "git").unwrap_or_default();
    let mut env = Vec::new();
    let (name, email) = (s.name.trim(), s.email.trim());
    if !name.is_empty() {
        env.push(("GIT_AUTHOR_NAME".to_string(), name.to_string()));
        env.push(("GIT_COMMITTER_NAME".to_string(), name.to_string()));
    }
    if !email.is_empty() {
        env.push(("GIT_AUTHOR_EMAIL".to_string(), email.to_string()));
        env.push(("GIT_COMMITTER_EMAIL".to_string(), email.to_string()));
    }
    env
}

pub fn home_of(app: &App, user: &User) -> PathBuf {
    app.data_dir().join("users").join(&user.username).join("home")
}

/// Global git config for processes that run outside the sandbox (admins).
pub fn global_config(app: &App, user: &User) -> Option<PathBuf> {
    let p = home_of(app, user).join(".gitconfig");
    p.exists().then_some(p)
}

fn enc(s: &str) -> String {
    let mut out = String::new();
    for b in s.bytes() {
        match b {
            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => out.push(b as char),
            _ => out.push_str(&format!("%{b:02X}")),
        }
    }
    out
}

fn quote(s: &str) -> String {
    format!("\"{}\"", s.replace('\\', "\\\\").replace('"', "\\\""))
}

/// Write the credential store and config into the user's home.
pub fn write_files(app: &App, user: &User, settings: &GitSettings) -> Result<()> {
    let home = home_of(app, user);
    std::fs::create_dir_all(&home)?;
    let creds_path = home.join(".git-credentials");
    let mut creds = String::new();
    for c in &settings.credentials {
        if c.host.trim().is_empty() || c.token.is_empty() {
            continue;
        }
        let proto = if c.protocol == "http" { "http" } else { "https" };
        let (host, path) = match c.host.trim().trim_start_matches("https://").trim_start_matches("http://").split_once('/') {
            Some((h, p)) => (h.to_string(), format!("/{}", p.trim_matches('/'))),
            None => (c.host.trim().trim_start_matches("https://").trim_start_matches("http://").to_string(), String::new()),
        };
        creds.push_str(&format!("{proto}://{}:{}@{host}{path}\n", enc(c.username.trim()), enc(&c.token)));
    }
    std::fs::write(&creds_path, creds)?;
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;
        std::fs::set_permissions(&creds_path, std::fs::Permissions::from_mode(0o600))?;
    }

    // Managed part of the config. Two helpers: the absolute path works outside
    // the sandbox, the default (~/.git-credentials) inside it.
    let mut cfg = String::from("# Managed by CodeCraft (Settings → Account → Git). Do not edit.\n");
    if !settings.name.trim().is_empty() || !settings.email.trim().is_empty() {
        cfg.push_str("[user]\n");
        if !settings.name.trim().is_empty() {
            cfg.push_str(&format!("\tname = {}\n", quote(settings.name.trim())));
        }
        if !settings.email.trim().is_empty() {
            cfg.push_str(&format!("\temail = {}\n", quote(settings.email.trim())));
        }
    }
    cfg.push_str(&format!("[credential]\n\thelper = {}\n\thelper = store\n", quote(&format!("store --file={}", creds_path.display()))));
    // Matching credentials by path needs useHttpPath for entries with a path.
    if settings.credentials.iter().any(|c| c.host.trim().trim_start_matches("https://").contains('/')) {
        cfg.push_str("\tuseHttpPath = true\n");
    }
    std::fs::write(home.join(".gitconfig-codecraft"), cfg)?;

    let main = home.join(".gitconfig");
    let current = std::fs::read_to_string(&main).unwrap_or_default();
    if !current.contains(".gitconfig-codecraft") {
        let mut next = current;
        if !next.is_empty() && !next.ends_with('\n') {
            next.push('\n');
        }
        next.push_str("[include]\n\tpath = .gitconfig-codecraft\n");
        std::fs::write(&main, next)?;
    }
    Ok(())
}

/// Settings with tokens masked for the UI.
pub fn masked(settings: &GitSettings) -> GitSettings {
    let mut s = settings.clone();
    for c in &mut s.credentials {
        c.token = if c.token.is_empty() { String::new() } else { "••••••••".into() };
    }
    s
}

/// Merge an update from the UI: empty or masked tokens keep the stored token.
pub fn merge(old: &GitSettings, mut new: GitSettings) -> GitSettings {
    for c in &mut new.credentials {
        if c.token.is_empty() || c.token.chars().all(|ch| ch == '•') {
            if let Some(prev) = old.credentials.iter().find(|p| p.host == c.host && p.username == c.username) {
                c.token = prev.token.clone();
            }
        }
    }
    new
}

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

    #[test]
    fn keeps_masked_tokens() {
        let old = GitSettings { credentials: vec![GitCredential { host: "git.x".into(), username: "me".into(), token: "secret".into(), protocol: String::new() }], ..Default::default() };
        let upd = GitSettings { credentials: vec![GitCredential { host: "git.x".into(), username: "me".into(), token: "••••••••".into(), protocol: String::new() }], ..Default::default() };
        assert_eq!(merge(&old, upd).credentials[0].token, "secret");
        assert_eq!(enc("a@b:c/d"), "a%40b%3Ac%2Fd");
    }
}