// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <algorithm>

#include "common/logging/filter.h"
#include "common/logging/backend.h"
#include "common/string_util.h"

namespace Log {

Filter::Filter(Level default_level) {
    ResetAll(default_level);
}

void Filter::ResetAll(Level level) {
    class_levels.fill(level);
}

void Filter::SetClassLevel(Class log_class, Level level) {
    class_levels[static_cast<size_t>(log_class)] = level;
}

void Filter::SetSubclassesLevel(const ClassInfo& log_class, Level level) {
    const size_t log_class_i = static_cast<size_t>(log_class.log_class);

    const size_t begin = log_class_i + 1;
    const size_t end = begin + log_class.num_children;
    for (size_t i = begin; begin < end; ++i) {
        class_levels[i] = level;
    }
}

void Filter::ParseFilterString(const std::string& filter_str) {
    auto clause_begin = filter_str.cbegin();
    while (clause_begin != filter_str.cend()) {
        auto clause_end = std::find(clause_begin, filter_str.cend(), ' ');

        // If clause isn't empty
        if (clause_end != clause_begin) {
            ParseFilterRule(clause_begin, clause_end);
        }

        if (clause_end != filter_str.cend()) {
            // Skip over the whitespace
            ++clause_end;
        }
        clause_begin = clause_end;
    }
}

template <typename It>
static Level GetLevelByName(const It begin, const It end) {
    for (u8 i = 0; i < static_cast<u8>(Level::Count); ++i) {
        const char* level_name = Logger::GetLevelName(static_cast<Level>(i));
        if (Common::ComparePartialString(begin, end, level_name)) {
            return static_cast<Level>(i);
        }
    }
    return Level::Count;
}

template <typename It>
static Class GetClassByName(const It begin, const It end) {
    for (ClassType i = 0; i < static_cast<ClassType>(Class::Count); ++i) {
        const char* level_name = Logger::GetLogClassName(static_cast<Class>(i));
        if (Common::ComparePartialString(begin, end, level_name)) {
            return static_cast<Class>(i);
        }
    }
    return Class::Count;
}

template <typename InputIt, typename T>
static InputIt find_last(InputIt begin, const InputIt end, const T& value) {
    auto match = end;
    while (begin != end) {
        auto new_match = std::find(begin, end, value);
        if (new_match != end) {
            match = new_match;
            ++new_match;
        }
        begin = new_match;
    }
    return match;
}

bool Filter::ParseFilterRule(const std::string::const_iterator begin,
        const std::string::const_iterator end) {
    auto level_separator = std::find(begin, end, ':');
    if (level_separator == end) {
        LOG_ERROR(Log, "Invalid log filter. Must specify a log level after `:`: %s",
                std::string(begin, end).c_str());
        return false;
    }

    const Level level = GetLevelByName(level_separator + 1, end);
    if (level == Level::Count) {
        LOG_ERROR(Log, "Unknown log level in filter: %s", std::string(begin, end).c_str());
        return false;
    }

    if (Common::ComparePartialString(begin, level_separator, "*")) {
        ResetAll(level);
        return true;
    }

    auto class_name_end = find_last(begin, level_separator, '.');
    if (class_name_end != level_separator &&
            !Common::ComparePartialString(class_name_end + 1, level_separator, "*")) {
        class_name_end = level_separator;
    }

    const Class log_class = GetClassByName(begin, class_name_end);
    if (log_class == Class::Count) {
        LOG_ERROR(Log, "Unknown log class in filter: %s", std::string(begin, end).c_str());
        return false;
    }

    if (class_name_end == level_separator) {
        SetClassLevel(log_class, level);
    }
    SetSubclassesLevel(log_class, level);
    return true;
}

bool Filter::CheckMessage(Class log_class, Level level) const {
    return static_cast<u8>(level) >= static_cast<u8>(class_levels[static_cast<size_t>(log_class)]);
}

}