// Copyright (c) The Geekeey Authors
// SPDX-License-Identifier: EUPL-1.2

using System.CommandLine;
using System.Text;

namespace Geekeey.Actions.Core.Commands;

internal sealed class Checkout : Command
{
#pragma warning disable format // @formatter:off
	private static readonly Option<Uri> Repository = new("--repository") { Required = true };
	private static readonly Option<DirectoryInfo> Destination = new("--path") { Required = true };
	private static readonly Option<string> Reference = new("--reference") { Required = true };
#pragma warning restore format // @formatter:on

	internal Checkout() : base("checkout")
	{
		Add(Repository);
		Add(Destination);
		Add(Reference);

		SetAction(HandleAsync);
	}

	private async Task<int> HandleAsync(ParseResult result, CancellationToken cancellationToken)
	{
		var server = result.GetRequiredValue(Program.Server);
		var access = result.GetRequiredValue(Program.Token);

		var workspace = result.GetRequiredValue(Destination);

		await $"git init -q {workspace.FullName}";
		await $"git -C {workspace.FullName} config set --local protocol.version 2";
		await $"git -C {workspace.FullName} config set --local gc.auto 0";

		var repository = result.GetRequiredValue(Repository);

		if (!repository.IsAbsoluteUri)
		{
			// relative repository urls are resolved against the server url
			repository = new Uri(server, repository);

			await $"git -C {workspace.FullName} config set --local --append url.{repository}.insteadOf git@{repository.Host}";
			await $"git -C {workspace.FullName} config set --local --append url.{repository}.insteadOf ssh://git@{repository.Host}";
			await $"git -C {workspace.FullName} config set --local --append url.{repository}.insteadOf git://{repository.Host}";

			var header = $"Authorization: Basic {Convert.ToBase64String(Encoding.UTF8.GetBytes($"x-access-token::${access}"))}";
			await $"git -C {workspace.FullName} config set --local http.{repository}.extraheader '{header}'";
		}

		var origin = "origin";
		var reference = result.GetRequiredValue(Reference);

		await $"git -C {workspace.FullName} remote add {origin} {repository}";
		var list = (await $"git -C {workspace.FullName} ls-remote {origin} {reference}").Split('\t');

		if (list.Length < 2)
		{
			throw new InvalidOperationException("git ls-remote resolved nothing");
		}

		var @sha = list[0].Trim();
		var @ref = list[1].Trim();

		if (@ref.TryCutPrefix("refs/heads/", out var name))
		{
			var remote = $"refs/remotes/{origin}/{name}";
			var branch = name;

			await $"git -C {workspace.FullName} fetch --no-tags --prune --no-recurse-submodules --depth=1 {origin} +{@sha}:{remote}";
			await $"git -C {workspace.FullName} checkout --force -B {branch} {remote}";
		}
		else if (@ref.TryCutPrefix("refs/pull/", out name))
		{
			var remote = $"refs/remotes/pull/{name}";

			// Best-effort parity with the Go code's env.BaseRef/env.HeadRef:
			var baseRef = Environment.GetEnvironmentVariable("GITHUB_BASE_REF");
			var headRef = Environment.GetEnvironmentVariable("GITHUB_HEAD_REF");

			var branch =
				!string.IsNullOrEmpty(baseRef) ? baseRef :
				!string.IsNullOrEmpty(headRef) ? headRef :
				throw new InvalidOperationException("pull request can not find base ref for branch");

			await $"git -C {workspace.FullName} fetch --no-tags --prune --no-recurse-submodules --depth=1 {origin} +{@sha}:{remote}";
			await $"git -C {workspace.FullName} checkout --force -B {branch} {branch}";
		}
		else if (@ref.TryCutPrefix("refs/tags/", out name))
		{
			var remote = $"refs/tags/{name}";

			await $"git -C {workspace.FullName} fetch --no-tags --prune --no-recurse-submodules --depth=1 {origin} +{@sha}:{remote}";
			await $"git -C {workspace.FullName} checkout --force {remote}";
		}
		else
		{
			await $"git -C {workspace.FullName} fetch --no-tags --prune --no-recurse-submodules --depth=1 {origin} {@ref}";
			await $"git -C {workspace.FullName} checkout --force {@ref}";
		}

		return 0;
	}
}