#include "cli/options.hpp"

#include <algorithm>
#include <charconv>
#include <cstdint>
#include <cstring>
#include <sstream>

#include "core/canvas.hpp"
#include "core/chain.hpp"
#include "core/effect.hpp"
#include "core/registry.hpp"

namespace effector {
namespace {

bool parseLong(const std::string& text, long& out) {
    const char* begin = text.data();
    const char* end = begin + text.size();
    const auto result = std::from_chars(begin, end, out);
    return result.ec == std::errc{} && result.ptr == end;
}

bool parseSize(const std::string& text, int& width, int& height) {
    const auto sep = text.find_first_of("xX*,");
    if (sep == std::string::npos) return false;
    long w = 0;
    long h = 0;
    if (!parseLong(text.substr(0, sep), w) || !parseLong(text.substr(sep + 1), h)) return false;
    // Checked as longs, before the narrowing: 4294968296 cast straight to int
    // is 1000, which would render a plausible canvas nobody asked for.
    if (w < kMinCanvasSide || w > kMaxCanvasSide) return false;
    if (h < kMinCanvasSide || h > kMaxCanvasSide) return false;
    width = static_cast<int>(w);
    height = static_cast<int>(h);
    return true;
}

// Every effect's params share one flag namespace, exactly as in the interface.
const ParamSpec* findSpec(const std::string& flag) {
    for (const auto& effect : effects()) {
        for (const auto& spec : effect->params()) {
            if (spec.flag() == flag) return &spec;
        }
    }
    return nullptr;
}

std::string requireValue(int argc, char** argv, int& i, const std::string& flag) {
    if (i + 1 >= argc) throw EffectError(flag + " needs a value");
    return argv[++i];
}

}  // namespace

Options parseOptions(int argc, char** argv) {
    Options options;

    for (int i = 1; i < argc; ++i) {
        const std::string arg = argv[i];

        if (arg == "-h" || arg == "--help") {
            options.showHelp = true;
        } else if (arg == "--list-effects") {
            options.listEffects = true;
        } else if (arg == "-e" || arg == "--effect") {
            const std::string name = requireValue(argc, argv, i, arg);
            effectByName(name);  // validate now, fail early
            options.effects.push_back(name);
        } else if (arg == "-o" || arg == "--output") {
            options.output = requireValue(argc, argv, i, arg);
        } else if (arg == "-s" || arg == "--size") {
            const std::string value = requireValue(argc, argv, i, arg);
            if (!parseSize(value, options.width, options.height)) {
                throw EffectError("invalid size '" + value + "', expected e.g. 1920x1080 with "
                                  "each side between " + std::to_string(kMinCanvasSide) + " and " +
                                  std::to_string(kMaxCanvasSide));
            }
        } else if (arg == "--format") {
            const std::string value = requireValue(argc, argv, i, arg);
            if (canvasFormatByKey(value) == nullptr) {
                throw EffectError("unknown canvas format '" + value + "', see --help");
            }
            options.format = value;
        } else if (arg == "--dpi") {
            const std::string value = requireValue(argc, argv, i, arg);
            long dpi = 0;
            if (!parseLong(value, dpi) || dpi < kMinDpi || dpi > kMaxDpi) {
                throw EffectError("invalid dpi '" + value + "', expected " +
                                  std::to_string(kMinDpi) + "-" + std::to_string(kMaxDpi));
            }
            options.dpi = static_cast<int>(dpi);
        } else if (arg == "--disable") {
            const std::string name = requireValue(argc, argv, i, arg);
            effectByName(name);  // validate now, exactly as -e does
            options.disabled.push_back(name);
        } else if (arg == "--seed") {
            const std::string value = requireValue(argc, argv, i, arg);
            long seed = 0;
            if (!parseLong(value, seed)) throw EffectError("invalid seed '" + value + "'");
            options.seed = static_cast<std::uint64_t>(seed);
        } else if (arg.rfind("--no-", 0) == 0) {
            const std::string flag = "--" + arg.substr(5);
            const ParamSpec* spec = findSpec(flag);
            if (spec == nullptr || spec->type != ParamSpec::Type::Bool) {
                throw EffectError("unknown option '" + arg + "'");
            }
            options.params[spec->key] = false;
        } else if (arg.rfind("--", 0) == 0) {
            const ParamSpec* spec = findSpec(arg);
            if (spec == nullptr) throw EffectError("unknown option '" + arg + "'");
            switch (spec->type) {
                case ParamSpec::Type::Bool:
                    options.params[spec->key] = true;
                    break;
                case ParamSpec::Type::Int: {
                    long value = 0;
                    const std::string text = requireValue(argc, argv, i, arg);
                    if (!parseLong(text, value)) {
                        throw EffectError(arg + ": '" + text + "' is not a whole number");
                    }
                    options.params[spec->key] = value;
                    break;
                }
                case ParamSpec::Type::Double: {
                    const std::string text = requireValue(argc, argv, i, arg);
                    try {
                        options.params[spec->key] = std::stod(text);
                    } catch (const std::exception&) {
                        throw EffectError(arg + ": '" + text + "' is not a number");
                    }
                    break;
                }
                case ParamSpec::Type::Path:
                case ParamSpec::Type::Text:
                    options.params[spec->key] = requireValue(argc, argv, i, arg);
                    break;
                case ParamSpec::Type::Color: {
                    const std::string text = requireValue(argc, argv, i, arg);
                    std::uint8_t rgb[3];
                    if (!parseColor(text, rgb)) {
                        throw EffectError(arg + ": '" + text +
                                          "' is not a colour, expected e.g. #ff8800");
                    }
                    options.params[spec->key] = formatColor(rgb);
                    break;
                }
                case ParamSpec::Type::Choice: {
                    const std::string text = requireValue(argc, argv, i, arg);
                    bool valid = false;
                    for (const auto& choice : spec->choices) valid = valid || choice == text;
                    if (!valid) throw EffectError(arg + ": unknown value '" + text + "'");
                    options.params[spec->key] = text;
                    break;
                }
            }
        } else if (arg.rfind("-", 0) == 0 && arg.size() > 1) {
            throw EffectError("unknown option '" + arg + "'");
        } else {
            options.images.push_back(arg);
        }
    }
    // Applied once everything is parsed, so --dpi may come before --format and
    // so a format always wins over an -s given alongside it.
    if (const auto* format = canvasFormatByKey(options.format)) {
        canvasFormatSize(*format, options.dpi, options.width, options.height);
    }
    return options;
}

std::string usage(const char* programName) {
    std::ostringstream out;
    out << "Usage: " << programName << " [options] [image ...]\n\n"
        << "Image effects app. Runs the GTK interface unless --output is given.\n\n"
        << "Options:\n"
        << "  -e, --effect NAME     effect to apply, repeat to cascade (--output"
           " defaults to " << defaultEffectName() << ")\n"
        << "  -o, --output FILE     render headlessly to this file and exit\n"
        << "  -s, --size WxH        canvas size, each side " << kMinCanvasSide << "-"
        << kMaxCanvasSide << " (default: 1920x1080)\n"
        << "      --format NAME     canvas format, overrides --size (see below)\n"
        << "      --dpi N           resolution of a print format, " << kMinDpi << "-" << kMaxDpi
        << " (default: " << kDefaultDpi << ")\n"
        << "      --disable NAME    keep this effect in the chain but skip it\n"
        << "      --seed N          random seed (default: random)\n"
        << "      --list-effects    list available effects and exit\n"
        << "  -h, --help            show this help and exit\n";

    out << "\nCanvas formats (--format):\n";
    for (const auto& format : canvasFormats()) {
        out << "  " << format.key;
        if (format.key.size() < 20) out << std::string(20 - format.key.size(), ' ');
        out << "  " << format.label << ", " << canvasFormatDetail(format)
            << (format.print ? " at --dpi" : "") << "\n";
    }

    for (const auto& effect : effects()) {
        out << "\n" << effect->title() << " options:\n";
        for (const auto& spec : effect->params()) {
            std::string flag = spec.flag();
            if (spec.type != ParamSpec::Type::Bool) flag += " VALUE";
            out << "  " << flag;
            if (flag.size() < 20) out << std::string(20 - flag.size(), ' ');
            out << "  " << (spec.help.empty() ? spec.label : spec.help) << "\n";
        }
    }
    return out.str();
}

std::vector<ChainStage> buildChain(const Options& options) {
    std::vector<ChainStage> stages;
    for (const auto& name : options.effects) {
        ChainStage stage;
        stage.effect = effectByName(name);
        stage.values = stage.effect->defaults();
        stage.enabled = std::find(options.disabled.begin(), options.disabled.end(), name) ==
                        options.disabled.end();
        for (const auto& spec : stage.effect->params()) {
            const auto it = options.params.find(spec.key);
            if (it != options.params.end()) stage.values[spec.key] = it->second;
        }
        stages.push_back(std::move(stage));
    }
    return stages;
}

}  // namespace effector