import { dirname } from "path";
import { fileURLToPath } from "url"

import { run } from "./run.js";

const __filename = fileURLToPath(import.meta.url)
const __dirname = dirname(__filename)

// Returns the most recent git commit hash for a given filename
export async function getGitTag(filename: string): Promise<null | string> {
    const result = await run("git", [ "log", "-n", "1", "--", filename ], __dirname);
    if (!result.ok) { throw new Error(`git log error`); }

    let log = result.stdout.trim();
    if (!log) { return null; }

    const hashMatch = log.match(/^commit\s+([0-9a-f]{40})\n/i);
    if (!hashMatch) { return null; }
    return hashMatch[1];
}

export async function getModifiedTime(filename: string): Promise<null | number> {
    const result = await run("git", [ "log", "-n", "1", "--", filename ], __dirname);
    if (!result.ok) { throw new Error(`git log error`); }

    let log = result.stdout.trim();
    if (!log) { return null; }

    for (let line of log.split("\n")) {
        line = line.trim();
        if (!line) { break; }
        const match = line.match(/^date:\s+(.*)$/i);
        if (match) {
            return (new Date(match[1].trim())).getTime();;
        }
    }

    return null;
}

export interface GitLog {
    commit: string;
    author: string;
    date: string;
    body: string;
}

export async function getLogs(files?: null | Array<string>, range?: null | { tag0: string, tag1: string }, limit?: null | number): Promise<Array<GitLog>> {
    const args = [ "log", "-n", String((limit != null) ? limit: 100) ];

    if (range) {
        args.push(`${ range.tag0 }..${ range.tag1 }`);
    }

    if (files) {
        args.push("--");
        files.forEach((f) => args.push(f));
    }

    const exec = await run("git", args);
    if (!exec.ok) { throw new Error(`git log error`); }

    const log = exec.stdout.trim();
    if (!log) { return [ ]; }

    const results: Array<GitLog> = [ { commit: "", author: "", date: "", body: "" } ];
    for (const line of log.split("\n")) {
        const hashMatch = line.match(/^commit\s+([0-9a-f]{40})/i);
         if (hashMatch) {
             results.push({ commit: hashMatch[1], author: "", date: "", body: "" });
         } else {
             if (line.startsWith("Author:")) {
                 results[results.length - 1].author = line.substring(7).trim();
             } else if (line.startsWith("Date:")) {
                 results[results.length - 1].date = line.substring(5).trim();
             } else {
                 results[results.length - 1].body = (results[results.length - 1].body + " " + line).trim();
             }
         }
    }

    // Nix the bootstrap entry
    results.shift();

    return results;
}

export async function getDiff(filename: string, tag0: string, tag1: string): Promise<string> {
    const result = await run("git", [ "diff", `${ tag0 }..${ tag1 }`, "--", filename ]);
    if (!result.ok) { throw new Error(`git log error`); }
    return result.stdout.trim();
}

export async function getTags(): Promise<Array<string>> {
    const result = await run("git", [ "tag" ]);
    if (!result.ok) { throw new Error(`git log error`); }
    return result.stdout.trim().split("\n");
}