#include "ScheduleValidator.h"

namespace timbre_core {
namespace {

ValidationResult failure(ValidationCode code, std::size_t index = 0) noexcept {
    return ValidationResult(code, index);
}

} // namespace

const char* ValidationResult::message() const noexcept {
    switch (code) {
        case ValidationCode::Ok:
            return "ok";
        case ValidationCode::TooManyProfiles:
            return "too many profiles";
        case ValidationCode::TooManyPatterns:
            return "too many patterns";
        case ValidationCode::TooManySchedules:
            return "too many schedules";
        case ValidationCode::TooManyHolidays:
            return "too many holidays";
        case ValidationCode::InvalidProfileId:
            return "invalid profile id";
        case ValidationCode::DuplicateProfileId:
            return "duplicate profile id";
        case ValidationCode::InvalidPatternId:
            return "invalid pattern id";
        case ValidationCode::DuplicatePatternId:
            return "duplicate pattern id";
        case ValidationCode::InvalidPhaseCount:
            return "invalid phase count";
        case ValidationCode::InvalidPhaseDuration:
            return "invalid phase duration";
        case ValidationCode::PatternTotalTooLarge:
            return "pattern total is too large";
        case ValidationCode::InvalidHolidayId:
            return "invalid holiday id";
        case ValidationCode::DuplicateHolidayId:
            return "duplicate holiday id";
        case ValidationCode::InvalidHolidayDate:
            return "invalid holiday date";
        case ValidationCode::InvalidScheduleId:
            return "invalid schedule id";
        case ValidationCode::DuplicateScheduleId:
            return "duplicate schedule id";
        case ValidationCode::InvalidMinute:
            return "invalid minute";
        case ValidationCode::InvalidWeekdayMask:
            return "invalid weekday mask";
        case ValidationCode::UnknownProfile:
            return "schedule references an unknown profile";
        case ValidationCode::UnknownPattern:
            return "schedule references an unknown pattern";
        case ValidationCode::InvalidActiveProfile:
            return "active profile does not exist";
    }
    return "validation error";
}

ValidationResult ScheduleValidator::validateProfile(const Profile& profile,
                                                    std::size_t index) noexcept {
    if (profile.id == kInvalidId) {
        return failure(ValidationCode::InvalidProfileId, index);
    }
    return ValidationResult{};
}

ValidationResult ScheduleValidator::validatePattern(const Pattern& pattern,
                                                    std::size_t index) noexcept {
    if (!isPatternId(pattern.id)) {
        return failure(ValidationCode::InvalidPatternId, index);
    }
    if (pattern.phaseCount > kMaxPatternPhases) {
        return failure(ValidationCode::InvalidPhaseCount, index);
    }

    std::uint16_t total = 0;
    for (std::size_t i = 0; i < pattern.phaseCount; ++i) {
        if (!validPhaseDuration(pattern.phases[i])) {
            return failure(ValidationCode::InvalidPhaseDuration, index);
        }
        total = static_cast<std::uint16_t>(total + pattern.phases[i]);
        if (!validPatternTotal(total)) {
            return failure(ValidationCode::PatternTotalTooLarge, index);
        }
    }
    return ValidationResult{};
}

ValidationResult ScheduleValidator::validateHoliday(const Holiday& holiday,
                                                    std::size_t index) noexcept {
    if (holiday.id == kInvalidId) {
        return failure(ValidationCode::InvalidHolidayId, index);
    }
    if (!validHolidayDate(holiday.month, holiday.day)) {
        return failure(ValidationCode::InvalidHolidayDate, index);
    }
    return ValidationResult{};
}

bool ScheduleValidator::validHolidayDate(std::uint8_t month, std::uint8_t day) noexcept {
    // Holidays are recurring month/day values.  February 29 is valid and is
    // naturally inert in non-leap years.
    if (month < 1 || month > 12 || day < 1) {
        return false;
    }
    static constexpr std::uint8_t maximumDays[] = {
        0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
    };
    return day <= maximumDays[month];
}

ValidationResult ScheduleValidator::validateSchedule(const Schedule& schedule,
                                                     const AppState& state,
                                                     std::size_t index) noexcept {
    if (schedule.id == kInvalidId) {
        return failure(ValidationCode::InvalidScheduleId, index);
    }
    if (!validMinute(schedule.minuteOfDay)) {
        return failure(ValidationCode::InvalidMinute, index);
    }
    if (!validWeekdayMask(schedule.weekdayMask)) {
        return failure(ValidationCode::InvalidWeekdayMask, index);
    }
    if (state.profile(schedule.profileId) == nullptr) {
        return failure(ValidationCode::UnknownProfile, index);
    }
    if (state.pattern(schedule.patternId) == nullptr ||
        !isPatternId(schedule.patternId)) {
        return failure(ValidationCode::UnknownPattern, index);
    }
    const Pattern* pattern = state.pattern(schedule.patternId);
    if (pattern == nullptr || !validatePattern(*pattern).valid) {
        return failure(ValidationCode::UnknownPattern, index);
    }
    return ValidationResult{};
}

ValidationResult ScheduleValidator::validate(const AppState& state) noexcept {
    if (state.profiles.size() > kMaxProfiles) {
        return failure(ValidationCode::TooManyProfiles, state.profiles.size());
    }
    if (state.patterns.size() != kMaxPatterns) {
        return failure(ValidationCode::TooManyPatterns, state.patterns.size());
    }
    if (state.schedules.size() > kMaxSchedules) {
        return failure(ValidationCode::TooManySchedules, state.schedules.size());
    }
    if (state.holidays.size() > kMaxHolidays) {
        return failure(ValidationCode::TooManyHolidays, state.holidays.size());
    }

    for (std::size_t i = 0; i < state.profiles.size(); ++i) {
        const ValidationResult result = validateProfile(state.profiles[i], i);
        if (!result.valid) {
            return result;
        }
        for (std::size_t j = 0; j < i; ++j) {
            if (state.profiles[j].id == state.profiles[i].id) {
                return failure(ValidationCode::DuplicateProfileId, i);
            }
        }
    }

    for (std::size_t i = 0; i < state.patterns.size(); ++i) {
        const ValidationResult result = validatePattern(state.patterns[i], i);
        if (!result.valid) {
            return result;
        }
        for (std::size_t j = 0; j < i; ++j) {
            if (state.patterns[j].id == state.patterns[i].id) {
                return failure(ValidationCode::DuplicatePatternId, i);
            }
        }
    }

    for (std::size_t i = 0; i < state.holidays.size(); ++i) {
        const ValidationResult result = validateHoliday(state.holidays[i], i);
        if (!result.valid) {
            return result;
        }
        for (std::size_t j = 0; j < i; ++j) {
            if (state.holidays[j].id == state.holidays[i].id) {
                return failure(ValidationCode::DuplicateHolidayId, i);
            }
            if (state.holidays[j].enabled && state.holidays[i].enabled &&
                state.holidays[j].month == state.holidays[i].month &&
                state.holidays[j].day == state.holidays[i].day) {
                return failure(ValidationCode::DuplicateHolidayId, i);
            }
        }
    }

    for (std::size_t i = 0; i < state.schedules.size(); ++i) {
        const ValidationResult result = validateSchedule(state.schedules[i], state, i);
        if (!result.valid) {
            return result;
        }
        for (std::size_t j = 0; j < i; ++j) {
            if (state.schedules[j].id == state.schedules[i].id) {
                return failure(ValidationCode::DuplicateScheduleId, i);
            }
        }
    }

    if (state.profiles.size() != 0 && state.profile(state.activeProfileId) == nullptr) {
        return failure(ValidationCode::InvalidActiveProfile, 0);
    }
    return ValidationResult{};
}

} // namespace timbre_core