// SPDX-License-Identifier: AGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

module Crafter.Review:Artifact_impl;
import :Artifact;
import :Text;
import :Crypto;
import :Platform;
import :Process;
import std;

namespace fs = std::filesystem;

namespace Crafter::Review::Artifact {
    namespace {
        std::string ReadBytes(const fs::path& path) {
            std::optional<std::string> bytes = Platform::ReadFile(path);
            if (!bytes) throw std::runtime_error(std::format("{}: cannot read", path.string()));
            return std::move(*bytes);
        }

        // Four decimal digits and a '-' at `at`, as (\d{4})-: the number.
        std::optional<std::int64_t> FourDigits(std::string_view name, std::size_t at) {
            std::size_t end = at;
            for (std::int32_t i = 0; i < 4; ++i) {
                if (end >= name.size()) return std::nullopt;
                const auto [c, used] = Dyn::CodePointAt(name, end);
                if (!Dyn::IsDecimal(c)) return std::nullopt;
                end += used;
            }
            if (end >= name.size() || name[end] != '-') return std::nullopt;
            return Dyn::ParseInt(name.substr(at, end - at));
        }
    }

    std::string Sha256File(const fs::path& path) {
        return Sha256Hex(ReadBytes(path));
    }

    std::string ArtifactHash(std::string_view mode, const fs::path& path) {
        if (mode == "reply") return Sha256File(path);
        std::string all;
        for (const std::string& name : PatchFiles(path)) all += ReadBytes(path / name);
        return Sha256Hex(all);
    }

    std::vector<std::string> PatchFiles(const fs::path& path) {
        std::vector<std::string> out;
        for (const fs::directory_entry& entry : fs::directory_iterator(path)) {
            std::string name = entry.path().filename().string();
            if (name.ends_with(".patch")) out.push_back(std::move(name));
        }
        std::ranges::sort(out);
        return out;
    }

    std::optional<std::int64_t> PatchNumber(std::string_view name) {
        if (name.starts_with('v')) {
            const std::size_t digits = Dyn::DecimalRun(name, 1);
            if (digits > 0 && 1 + digits < name.size() && name[1 + digits] == '-') {
                if (const std::optional<std::int64_t> k = FourDigits(name, 2 + digits)) return k;
            }
        }
        return FourDigits(name, 0);
    }

    std::map<std::int64_t, std::string> PatchTexts(const fs::path& path) {
        std::map<std::int64_t, std::string> out;
        for (const std::string& name : PatchFiles(path)) {
            const std::optional<std::int64_t> k = PatchNumber(name);
            if (!k) throw Dyn::Error("AttributeError", "'NoneType' object has no attribute 'group'");
            out[*k] = Dyn::ReadText(path / name);
        }
        return out;
    }

    std::optional<std::string> PatchHead(const fs::path& path) {
        const std::vector<std::string> files = PatchFiles(path);
        if (files.empty()) return std::nullopt;
        // open(errors='replace').readline().split(): the first line, universal
        // newlines and all.
        const std::string text = Dyn::UniversalNewlines(Dyn::DecodeReplace(ReadBytes(path / files.back())));
        const std::vector<std::string> first = Dyn::Split(std::string_view(text).substr(0, text.find('\n')));
        if (first.size() > 1 && first[0] == "From" && Dyn::Length(first[1]) == 40) return first[1];
        return std::nullopt;
    }

    std::string Git(const fs::path& tree, std::span<const std::string> args) {
        std::vector<std::string> argv = {"git", "-C", tree.string()};
        argv.insert(argv.end(), args.begin(), args.end());
        const Process::Captured run = Process::Run(argv);
        if (run.returnCode != 0) {
            const std::string& said = run.err.empty() ? run.out : run.err;
            throw Dyn::Error("RuntimeError", std::format("git -C {} {}: {}", tree.string(), Dyn::Join(args, " "),
                                                        Dyn::Strip(Dyn::UniversalNewlines(Dyn::DecodeReplace(said)))));
        }
        return Dyn::UniversalNewlines(Dyn::DecodeReplace(run.out));
    }

    bool IsToplevel(const fs::path& tree) {
        try {
            const std::string top = Dyn::Strip(Git(tree, std::array<std::string, 2>{"rev-parse", "--show-toplevel"}));
            return fs::weakly_canonical(fs::absolute(top)) == fs::weakly_canonical(fs::absolute(tree));
        } catch (const std::exception&) {
            return false;
        }
    }

    std::string TreeHead(const fs::path& tree) {
        return Dyn::Strip(Git(tree, std::array<std::string, 2>{"rev-parse", "HEAD"}));
    }

    std::string TreeDirty(const fs::path& tree) {
        return Dyn::Strip(Git(tree, std::array<std::string, 3>{"status", "--porcelain", "--untracked-files=no"}));
    }
}