#include "ConfigLoader.h"

#include <cstdint>
#include <sstream>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>

#include "toml.hpp"

namespace
{

// --- Error helpers --------------------------------------------------------

std::runtime_error makeError(const std::string& file,
                             const std::string& path,
                             const std::string& why)
{
    return std::runtime_error("Config: " + file + ": '" + path + "' " + why);
}

// --- Typed accessors (throw on missing or wrong type) ---------------------

int64_t requireInt(const toml::node_view<toml::node>& node,
                   const std::string& file,
                   const std::string& path)
{
    const std::optional<int64_t> value = node.value<int64_t>();
    if (!value)
    {
        throw makeError(file, path, "missing or not an integer");
    }
    return *value;
}

double requireDouble(const toml::node_view<toml::node>& node,
                     const std::string& file,
                     const std::string& path)
{
    if (const std::optional<double> v = node.value<double>())
    {
        return *v;
    }
    if (const std::optional<int64_t> v = node.value<int64_t>())
    {
        return static_cast<double>(*v);
    }
    throw makeError(file, path, "missing or not a number");
}

std::string requireString(const toml::node_view<toml::node>& node,
                          const std::string& file,
                          const std::string& path)
{
    const std::optional<std::string> value = node.value<std::string>();
    if (!value)
    {
        throw makeError(file, path, "missing or not a string");
    }
    return *value;
}

bool requireBool(const toml::node_view<toml::node>& node,
                 const std::string& file,
                 const std::string& path)
{
    const std::optional<bool> value = node.value<bool>();
    if (!value)
    {
        throw makeError(file, path, "missing or not a boolean");
    }
    return *value;
}

const toml::array& requireArray(const toml::node_view<toml::node>& node,
                                const std::string& file,
                                const std::string& path)
{
    const toml::array* arr = node.as_array();
    if (arr == nullptr)
    {
        throw makeError(file, path, "missing or not an array");
    }
    return *arr;
}

const toml::table& requireTable(const toml::node_view<toml::node>& node,
                                const std::string& file,
                                const std::string& path)
{
    const toml::table* tbl = node.as_table();
    if (tbl == nullptr)
    {
        throw makeError(file, path, "missing or not a table");
    }
    return *tbl;
}

Formula requireFormula(const toml::node_view<toml::node>& node,
                       const std::string& file,
                       const std::string& path)
{
    const std::string source = requireString(node, file, path);
    try
    {
        return Formula::compile(source);
    }
    catch (const std::exception& e)
    {
        throw makeError(file, path, std::string("formula error: ") + e.what());
    }
}

std::vector<std::string> requireStringArray(const toml::node_view<toml::node>& node,
                                            const std::string& file,
                                            const std::string& path)
{
    const toml::array& arr = requireArray(node, file, path);
    std::vector<std::string> result;
    result.reserve(arr.size());
    for (std::size_t i = 0; i < arr.size(); ++i)
    {
        const std::string elemPath = path + "[" + std::to_string(i) + "]";
        const std::optional<std::string> s = arr[i].value<std::string>();
        if (!s)
        {
            throw makeError(file, elemPath, "not a string");
        }
        result.push_back(*s);
    }
    return result;
}

std::vector<RecipeIngredient> parseIngredients(const toml::array& arr,
                                               const std::string& file,
                                               const std::string& path)
{
    std::vector<RecipeIngredient> result;
    result.reserve(arr.size());
    for (std::size_t i = 0; i < arr.size(); ++i)
    {
        const std::string elemPath = path + "[" + std::to_string(i) + "]";
        const toml::table* t = arr[i].as_table();
        if (t == nullptr)
        {
            throw makeError(file, elemPath, "not a table");
        }

        // We need a mutable node_view to reuse our helpers, which is fine
        // because the helpers never mutate.
        toml::table& mt = const_cast<toml::table&>(*t);

        RecipeIngredient ing;
        ing.item = requireString(mt["item"], file, elemPath + ".item");
        ing.amount = static_cast<int>(requireInt(mt["amount"], file, elemPath + ".amount"));
        result.push_back(std::move(ing));
    }
    return result;
}

std::vector<RecipeOutput> parseRecipeOutputs(const toml::array& arr,
                                             const std::string& file,
                                             const std::string& path)
{
    std::vector<RecipeOutput> result;
    result.reserve(arr.size());
    for (std::size_t i = 0; i < arr.size(); ++i)
    {
        const std::string elemPath = path + "[" + std::to_string(i) + "]";
        const toml::table* t = arr[i].as_table();
        if (t == nullptr)
        {
            throw makeError(file, elemPath, "not a table");
        }
        toml::table& mt = const_cast<toml::table&>(*t);

        RecipeOutput out;
        out.item = requireString(mt["item"], file, elemPath + ".item");
        out.amount = static_cast<int>(requireInt(mt["amount"], file, elemPath + ".amount"));
        if (const std::optional<double> p = mt["probability"].value<double>())
        {
            out.probability = *p;
        }
        else if (const std::optional<int64_t> p = mt["probability"].value<int64_t>())
        {
            out.probability = static_cast<double>(*p);
        }
        result.push_back(std::move(out));
    }
    return result;
}

toml::table parseFile(const std::string& path, const std::string& file)
{
    try
    {
        return toml::parse_file(path);
    }
    catch (const toml::parse_error& e)
    {
        std::ostringstream oss;
        oss << "Config: " << file << ": TOML parse error: " << e.description()
            << " at " << e.source().begin;
        throw std::runtime_error(oss.str());
    }
}

}  // namespace


// --- Per-file loaders -----------------------------------------------------

WorldConfig ConfigLoader::loadWorld(const std::string& path)
{
    const std::string file = "world.toml";
    toml::table tbl = parseFile(path, file);

    WorldConfig cfg;

    cfg.heightTiles                = static_cast<int>(requireInt(tbl["world"]["height_tiles"], file, "world.height_tiles"));
    cfg.refundPercentage           = static_cast<int>(requireInt(tbl["world"]["refund_percentage"], file, "world.refund_percentage"));
    cfg.startingBuildingBlocks     = static_cast<int>(requireInt(tbl["world"]["starting_building_blocks"], file, "world.starting_building_blocks"));
    cfg.scrapDespawnSeconds        = requireDouble(tbl["world"]["scrap_despawn_seconds"], file, "world.scrap_despawn_seconds");
    cfg.beltSpeedTilesPerSecond    = requireDouble(tbl["world"]["belt_speed_tiles_per_second"], file, "world.belt_speed_tiles_per_second");
    cfg.tunnelMaxDistance          = static_cast<int>(requireInt(tbl["world"]["tunnel_max_distance"], file, "world.tunnel_max_distance"));

    cfg.regions.asteroidWidth     = static_cast<int>(requireInt(tbl["regions"]["asteroid_width"],      file, "regions.asteroid_width"));
    cfg.regions.playerBufferWidth = static_cast<int>(requireInt(tbl["regions"]["player_buffer_width"], file, "regions.player_buffer_width"));
    cfg.regions.contestZoneWidth  = static_cast<int>(requireInt(tbl["regions"]["contest_zone_width"],  file, "regions.contest_zone_width"));
    cfg.regions.enemyBufferWidth  = static_cast<int>(requireInt(tbl["regions"]["enemy_buffer_width"],  file, "regions.enemy_buffer_width"));

    cfg.expansion.columnsPerExpansion = static_cast<int>(requireInt(tbl["expansion"]["columns_per_expansion"], file, "expansion.columns_per_expansion"));
    cfg.expansion.costBuildingBlocks  = static_cast<int>(requireInt(tbl["expansion"]["cost_building_blocks"],  file, "expansion.cost_building_blocks"));

    cfg.push.pushExpandColumns = static_cast<int>(requireInt(tbl["push"]["push_expand_columns"], file, "push.push_expand_columns"));
    cfg.push.scalingFactor     = requireDouble(tbl["push"]["scaling_factor"], file, "push.scaling_factor");

    cfg.waves.threatRateFormula    = requireFormula(tbl["waves"]["threat_rate_formula"], file, "waves.threat_rate_formula");
    cfg.waves.shipLevelFormula     = requireFormula(tbl["waves"]["ship_level_formula"],  file, "waves.ship_level_formula");
    cfg.waves.gapMinSeconds        = requireDouble(tbl["waves"]["gap_min_seconds"],       file, "waves.gap_min_seconds");
    cfg.waves.gapMaxSeconds        = requireDouble(tbl["waves"]["gap_max_seconds"],       file, "waves.gap_max_seconds");
    cfg.waves.spawnDurationSeconds = requireDouble(tbl["waves"]["spawn_duration_seconds"], file, "waves.spawn_duration_seconds");

    if (cfg.waves.gapMinSeconds > cfg.waves.gapMaxSeconds)
    {
        throw makeError(file, "waves", "gap_min_seconds > gap_max_seconds");
    }

    return cfg;
}

BuildingsConfig ConfigLoader::loadBuildings(const std::string& path)
{
    const std::string file = "buildings.toml";
    toml::table tbl = parseFile(path, file);

    BuildingsConfig cfg;
    const toml::array& arr = requireArray(tbl["building"], file, "building");

    for (std::size_t i = 0; i < arr.size(); ++i)
    {
        const std::string elemPath = "building[" + std::to_string(i) + "]";
        const toml::table* bt = arr[i].as_table();
        if (bt == nullptr)
        {
            throw makeError(file, elemPath, "not a table");
        }
        toml::table& mt = const_cast<toml::table&>(*bt);

        BuildingDef def;
        def.id                      = requireString(mt["id"],                        file, elemPath + ".id");
        def.cost                    = static_cast<int>(requireInt(mt["cost"],        file, elemPath + ".cost"));
        def.playerPlaceable         = requireBool(mt["player_placeable"],            file, elemPath + ".player_placeable");
        def.constructionTimeSeconds = requireDouble(mt["construction_time_seconds"], file, elemPath + ".construction_time_seconds");
        def.surfaceMask             = requireStringArray(mt["surface_mask"],         file, elemPath + ".surface_mask");

        const std::optional<BuildingType> parsedType = parseBuildingType(def.id);
        if (!parsedType)
        {
            throw makeError(file, elemPath + ".id", "unknown building id '" + def.id + "'");
        }
        def.type = *parsedType;

        cfg.buildings.push_back(std::move(def));
    }

    return cfg;
}

RecipesConfig ConfigLoader::loadRecipes(const std::string& path)
{
    const std::string file = "recipes.toml";
    toml::table tbl = parseFile(path, file);

    RecipesConfig cfg;
    const toml::array& arr = requireArray(tbl["recipe"], file, "recipe");

    for (std::size_t i = 0; i < arr.size(); ++i)
    {
        const std::string elemPath = "recipe[" + std::to_string(i) + "]";
        const toml::table* rt = arr[i].as_table();
        if (rt == nullptr)
        {
            throw makeError(file, elemPath, "not a table");
        }
        toml::table& mt = const_cast<toml::table&>(*rt);

        RecipeDef def;
        def.id              = requireString(mt["id"],              file, elemPath + ".id");
        def.durationSeconds = requireDouble(mt["duration_seconds"], file, elemPath + ".duration_seconds");

        const std::string buildingId = requireString(mt["building"], file, elemPath + ".building");
        const std::optional<BuildingType> parsedType = parseBuildingType(buildingId);
        if (!parsedType)
        {
            throw makeError(file, elemPath + ".building",
                            "unknown building id '" + buildingId + "'");
        }
        def.building = *parsedType;

        // inputs may be omitted (e.g. miner recipes). An empty array is fine.
        if (mt.contains("inputs"))
        {
            const toml::array& inputs = requireArray(mt["inputs"], file, elemPath + ".inputs");
            def.inputs = parseIngredients(inputs, file, elemPath + ".inputs");
        }

        const toml::array& outputs = requireArray(mt["outputs"], file, elemPath + ".outputs");
        def.outputs = parseRecipeOutputs(outputs, file, elemPath + ".outputs");

        cfg.recipes.push_back(std::move(def));
    }

    return cfg;
}

ShipsConfig ConfigLoader::loadShips(const std::string& path)
{
    const std::string file = "ships.toml";
    toml::table tbl = parseFile(path, file);

    ShipsConfig cfg;
    const toml::array& arr = requireArray(tbl["ship"], file, "ship");

    for (std::size_t i = 0; i < arr.size(); ++i)
    {
        const std::string elemPath = "ship[" + std::to_string(i) + "]";
        const toml::table* st = arr[i].as_table();
        if (st == nullptr)
        {
            throw makeError(file, elemPath, "not a table");
        }
        toml::table& mt = const_cast<toml::table&>(*st);

        ShipDef def;
        def.id                 = requireString(mt["id"],                 file, elemPath + ".id");
        def.availableFromStart = requireBool(mt["available_from_start"], file, elemPath + ".available_from_start");

        // Schematic
        {
            const std::string bpPath = elemPath + ".schematic";
            const toml::table& bpTable = requireTable(mt["schematic"], file, bpPath);
            toml::table& bpMt = const_cast<toml::table&>(bpTable);

            const toml::array& materials = requireArray(bpMt["materials"], file, bpPath + ".materials");
            def.schematic.materials = parseIngredients(materials, file, bpPath + ".materials");
            def.schematic.playerProductionLevel = static_cast<int>(requireInt(
                bpMt["player_production_level"], file, bpPath + ".player_production_level"));
            def.schematic.productionTimeSeconds = requireDouble(
                bpMt["production_time_seconds"], file, bpPath + ".production_time_seconds");
        }

        // Threat
        {
            const std::string tPath = elemPath + ".threat";
            const toml::table& tTable = requireTable(mt["threat"], file, tPath);
            toml::table& tMt = const_cast<toml::table&>(tTable);
            def.threat.costFormula = requireFormula(tMt["cost_formula"], file, tPath + ".cost_formula");
        }

        // Health
        {
            const std::string hPath = elemPath + ".health";
            const toml::table& hTable = requireTable(mt["health"], file, hPath);
            toml::table& hMt = const_cast<toml::table&>(hTable);
            def.health.hpFormula = requireFormula(hMt["hp_formula"], file, hPath + ".hp_formula");
        }

        // Movement
        {
            const std::string mPath = elemPath + ".movement";
            const toml::table& mTable = requireTable(mt["movement"], file, mPath);
            toml::table& mMt = const_cast<toml::table&>(mTable);
            def.movement.speedFormula = requireFormula(mMt["speed_formula"], file, mPath + ".speed_formula");
        }

        // Loot
        {
            const std::string lPath = elemPath + ".loot";
            const toml::table& lTable = requireTable(mt["loot"], file, lPath);
            toml::table& lMt = const_cast<toml::table&>(lTable);
            def.loot.scrapDrop = static_cast<int>(requireInt(lMt["scrap_drop"], file, lPath + ".scrap_drop"));
        }

        // Optional: combat
        if (mt.contains("combat"))
        {
            const std::string cPath = elemPath + ".combat";
            const toml::table& cTable = requireTable(mt["combat"], file, cPath);
            toml::table& cMt = const_cast<toml::table&>(cTable);
            ShipCombat combat {
                requireFormula(cMt["damage_formula"],       file, cPath + ".damage_formula"),
                requireFormula(cMt["attack_range_formula"], file, cPath + ".attack_range_formula"),
                requireFormula(cMt["attack_rate_formula"],  file, cPath + ".attack_rate_formula"),
            };
            def.combat = std::move(combat);
        }

        // Optional: salvage
        if (mt.contains("salvage"))
        {
            const std::string sPath = elemPath + ".salvage";
            const toml::table& sTable = requireTable(mt["salvage"], file, sPath);
            toml::table& sMt = const_cast<toml::table&>(sTable);
            ShipSalvage salvage;
            salvage.collectionRange = requireDouble(sMt["collection_range"], file, sPath + ".collection_range");
            salvage.cargoCapacity   = static_cast<int>(requireInt(sMt["cargo_capacity"], file, sPath + ".cargo_capacity"));
            def.salvage = salvage;
        }

        // Optional: repair
        if (mt.contains("repair"))
        {
            const std::string rPath = elemPath + ".repair";
            const toml::table& rTable = requireTable(mt["repair"], file, rPath);
            toml::table& rMt = const_cast<toml::table&>(rTable);
            ShipRepair repair {
                requireFormula(rMt["repair_rate_formula"],  file, rPath + ".repair_rate_formula"),
                requireFormula(rMt["repair_range_formula"], file, rPath + ".repair_range_formula"),
            };
            def.repair = std::move(repair);
        }

        cfg.ships.push_back(std::move(def));
    }

    return cfg;
}

StationsConfig ConfigLoader::loadStations(const std::string& path)
{
    const std::string file = "stations.toml";
    toml::table tbl = parseFile(path, file);

    StationsConfig cfg;

    // HQ
    {
        const std::string p = "hq";
        cfg.hq.surfaceMask = requireStringArray(tbl[p]["surface_mask"], file, p + ".surface_mask");
        cfg.hq.hpFormula   = requireFormula(tbl[p]["hp_formula"],       file, p + ".hp_formula");
    }

    // Player station
    {
        const std::string p = "player_station";
        cfg.playerStation.surfaceMask     = requireStringArray(tbl[p]["surface_mask"], file, p + ".surface_mask");
        cfg.playerStation.level           = static_cast<int>(requireInt(tbl[p]["level"], file, p + ".level"));
        cfg.playerStation.hpFormula       = requireFormula(tbl[p]["hp_formula"],        file, p + ".hp_formula");
        cfg.playerStation.damageFormula   = requireFormula(tbl[p]["damage_formula"],    file, p + ".damage_formula");
        cfg.playerStation.rangeFormula    = requireFormula(tbl[p]["range_formula"],     file, p + ".range_formula");
        cfg.playerStation.fireRateFormula = requireFormula(tbl[p]["fire_rate_formula"], file, p + ".fire_rate_formula");
        cfg.playerStation.scrapDropFormula = requireFormula(tbl[p]["scrap_drop_formula"], file, p + ".scrap_drop_formula");
    }

    // Enemy station
    {
        const std::string p = "enemy_station";
        cfg.enemyStation.surfaceMask      = requireStringArray(tbl[p]["surface_mask"], file, p + ".surface_mask");
        cfg.enemyStation.hpFormula        = requireFormula(tbl[p]["hp_formula"],         file, p + ".hp_formula");
        cfg.enemyStation.damageFormula    = requireFormula(tbl[p]["damage_formula"],     file, p + ".damage_formula");
        cfg.enemyStation.rangeFormula     = requireFormula(tbl[p]["range_formula"],      file, p + ".range_formula");
        cfg.enemyStation.fireRateFormula  = requireFormula(tbl[p]["fire_rate_formula"],  file, p + ".fire_rate_formula");
        cfg.enemyStation.scrapDropFormula = requireFormula(tbl[p]["scrap_drop_formula"], file, p + ".scrap_drop_formula");
    }

    return cfg;
}

GameConfig ConfigLoader::loadFromDirectory(const std::string& configDir)
{
    GameConfig cfg;
    cfg.world     = loadWorld(configDir + "/world.toml");
    cfg.buildings = loadBuildings(configDir + "/buildings.toml");
    cfg.recipes   = loadRecipes(configDir + "/recipes.toml");
    cfg.ships     = loadShips(configDir + "/ships.toml");
    cfg.stations  = loadStations(configDir + "/stations.toml");
    return cfg;
}