#include "./folders.hpp"

#include <cstdlib>
#include <ranges>

#include "../detect.hpp"
#include "../debug/assert.hpp"

#if MIJIN_TARGET_OS == MIJIN_OS_WINDOWS
#   include <Shlobj.h>
#endif

namespace mijin
{
fs::path getKnownFolder(KnownFolder folder) MIJIN_NOEXCEPT
{
#if MIJIN_TARGET_OS == MIJIN_OS_LINUX
    switch (folder)
    {
    case KnownFolder::USER_HOME:
        if (const char* val = std::getenv("HOME"); val != nullptr)
        {
            return val;
        }
        return "/";
    case KnownFolder::TEMP:
        for (const char* varname : {"TMPDIR", "TEMP", "TMP"})
        {
            if (const char* val = std::getenv(varname); val != nullptr)
            {
                return val;
            }
        }
        return "/tmp";
    case KnownFolder::CACHE_ROOT:
        if (const char* val = std::getenv("XDG_CACHE_HOME"); val != nullptr)
        {
            return val;
        }
        return getKnownFolder(KnownFolder::USER_HOME) / ".cache";
    case KnownFolder::USER_CONFIG_ROOT:
        if (const char* val = std::getenv("XDG_CONFIG_HOME"); val != nullptr)
        {
            return val;
        }
        return getKnownFolder(KnownFolder::USER_HOME) / ".config";
    case KnownFolder::USER_DATA_ROOT:
        if (const char* val = std::getenv("XDG_DATA_HOME"); val != nullptr)
        {
            return val;
        }
        return getKnownFolder(KnownFolder::USER_HOME) / ".local/share";
    }
    MIJIN_ERROR("Invalid value passed to getKnownFolder().");
    return {};
#elif MIJIN_TARGET_OS == MIJIN_OS_WINDOWS
    // TODO: this is 100% untested on Windows

    auto getKnownFolderPath = [](REFKNOWNFOLDERID rfid) -> fs::path
    {
        WCHAR* path = nullptr;
        if (!SUCCEEDED(SHGetKnownFolderPath(rfid, KF_FLAG_DEFAULT, nullptr, &path)))
        {
            CoTaskMemFree(path);
            return {};
        }
        fs::path result(path);
        CoTaskMemFree(path);
        return result;
    };

    switch (folder)
    {
    case KnownFolder::USER_HOME:
        if (const fs::path path = getKnownFolderPath(FOLDERID_Profile); !path.empty())
        {
            return path;
        }
        return "C:\\";
    case KnownFolder::TEMP:
    case KnownFolder::CACHE_ROOT:
        for (const char* varname : {"TMPDIR", "TEMP", "TMP"})
        {
            if (const char* val = std::getenv(varname); val != nullptr)
            {
                return val;
            }
        }
        return getKnownFolder(KnownFolder::USER_DATA_ROOT) / "Temp";
    case KnownFolder::USER_CONFIG_ROOT:
    case KnownFolder::USER_DATA_ROOT:
        if (const fs::path path = getKnownFolderPath(FOLDERID_LocalAppData); !path.empty())
        {
            return path;
        }
        return getKnownFolder(KnownFolder::USER_HOME) / "AppData" / "Local";
    }
    MIJIN_ERROR("Invalid value passed to getKnownFolder().");
    return {};
#else
    MIJIN_ERROR("Known folders not implemented for this platform.");
    return {}; // don't know :/
#endif
}

std::vector<fs::path> getAllConfigFolders(IncludeUser includeUser, IncludeSystem includeSystem) MIJIN_NOEXCEPT
{
    std::vector<fs::path> result;
    if (includeUser)
    {
        result.push_back(getKnownFolder(KnownFolder::USER_CONFIG_ROOT));
    }
#if MIJIN_TARGET_OS == MIJIN_OS_LINUX
    if (includeSystem)
    {
        if (const char* val = std::getenv("XDG_CONFIG_DIRS"); val != nullptr)
        {
            for (auto part : std::ranges::split_view(std::string_view(val), ':'))
            {
                result.emplace_back(part.begin(), part.end());
            }
        }
    }
#else
    (void) includeSystem;
#endif
    return result;
}

std::vector<fs::path> getAllDataFolders(IncludeUser includeUser, IncludeSystem includeSystem) MIJIN_NOEXCEPT
{
    std::vector<fs::path> result;
    if (includeUser)
    {
        result.push_back(getKnownFolder(KnownFolder::USER_DATA_ROOT));
    }
#if MIJIN_TARGET_OS == MIJIN_OS_LINUX
    if (includeSystem)
    {
        if (const char* val = std::getenv("XDG_DATA_DIRS"); val != nullptr)
        {
            for (auto part : std::ranges::split_view(std::string_view(val), ':'))
            {
                result.emplace_back(part.begin(), part.end());
            }
        }
    }
#else
    (void) includeSystem;
#endif
    return result;
}
}