#include "TimbreService.h"

#include <limits>

namespace timbre_core {
namespace {

bool containsProfile(const AppState& state, ProfileId id) noexcept {
    return state.profile(id) != nullptr;
}

bool containsSchedule(const AppState& state, ScheduleId id) noexcept {
    return state.schedule(id) != nullptr;
}

bool containsHoliday(const AppState& state, HolidayId id) noexcept {
    return state.holiday(id) != nullptr;
}

} // namespace

bool TimbreService::fail(ServiceCode code, const ValidationResult& validation) {
    lastResult_ = ServiceResult{false, code, validation};
    return false;
}

void TimbreService::observeIds(const AppState& state) noexcept {
    nextProfileId_.reset();
    nextScheduleId_.reset();
    nextHolidayId_.reset();
    for (std::size_t i = 0; i < state.profiles.size(); ++i) {
        nextProfileId_.observe(state.profiles[i].id);
    }
    for (std::size_t i = 0; i < state.schedules.size(); ++i) {
        nextScheduleId_.observe(state.schedules[i].id);
    }
    for (std::size_t i = 0; i < state.holidays.size(); ++i) {
        nextHolidayId_.observe(state.holidays[i].id);
    }
}

Id TimbreService::nextAvailableProfileId(const AppState& state) {
    for (;;) {
        const Id id = nextProfileId_.next();
        if (id != kInvalidId && !containsProfile(state, id)) {
            return id;
        }
    }
}

Id TimbreService::nextAvailableScheduleId(const AppState& state) {
    for (;;) {
        const Id id = nextScheduleId_.next();
        if (id != kInvalidId && !containsSchedule(state, id)) {
            return id;
        }
    }
}

Id TimbreService::nextAvailableHolidayId(const AppState& state) {
    for (;;) {
        const Id id = nextHolidayId_.next();
        if (id != kInvalidId && !containsHoliday(state, id)) {
            return id;
        }
    }
}

bool TimbreService::load() {
    AppState candidate;
    if (repository_ == nullptr || !repository_->load(candidate)) {
        return fail(ServiceCode::LoadFailed, ValidationResult{});
    }
    const ValidationResult validation = ScheduleValidator::validate(candidate);
    if (!validation.valid) {
        return fail(ServiceCode::InvalidRepositoryState, validation);
    }
    ram_ = candidate;
    observeIds(ram_);
    loaded_ = true;
    lastResult_ = ServiceResult{true, ServiceCode::Ok, ValidationResult{}};
    return true;
}

bool TimbreService::commitCurrent() {
    const ValidationResult validation = ScheduleValidator::validate(ram_);
    if (!validation.valid) {
        return fail(ServiceCode::ValidationFailed, validation);
    }
    if (repository_ == nullptr || !repository_->commit(ram_)) {
        return fail(ServiceCode::CommitFailed, ValidationResult{});
    }
    lastResult_ = ServiceResult{true, ServiceCode::Ok, ValidationResult{}};
    return true;
}

bool TimbreService::addProfile(const Profile& profile) {
    if (ram_.profiles.full()) {
        return fail(ServiceCode::LimitExceeded, ValidationResult{});
    }
    const ProfileId id = profile.id == kInvalidId ? nextAvailableProfileId(ram_) : profile.id;
    if (containsProfile(ram_, id)) {
        return fail(ServiceCode::DuplicateId, ValidationResult{});
    }
    Profile copy = profile;
    copy.id = id;
    const StableIdAllocator savedAllocator = nextProfileId_;
    const bool committed = transact([&copy](AppState& candidate) {
        if (!candidate.profiles.push_back(copy)) {
            return false;
        }
        if (candidate.profiles.size() == 1) {
            candidate.activeProfileId = copy.id;
        }
        return true;
    });
    if (!committed) {
        nextProfileId_ = savedAllocator;
    }
    return committed;
}

bool TimbreService::updateProfile(ProfileId id, const Profile& profile) {
    if (!containsProfile(ram_, id)) {
        return fail(ServiceCode::NotFound, ValidationResult{});
    }
    Profile copy = profile;
    copy.id = id;
    return transact([&copy](AppState& candidate) {
        Profile* target = candidate.profile(copy.id);
        if (target == nullptr) {
            return false;
        }
        *target = copy;
        return true;
    });
}

bool TimbreService::removeProfile(ProfileId id) {
    if (!containsProfile(ram_, id)) {
        return fail(ServiceCode::NotFound, ValidationResult{});
    }
    return transact([id](AppState& candidate) {
        std::size_t index = 0;
        for (; index < candidate.profiles.size(); ++index) {
            if (candidate.profiles[index].id == id) {
                break;
            }
        }
        if (index >= candidate.profiles.size() || !candidate.profiles.erase(index)) {
            return false;
        }
        if (candidate.activeProfileId == id) {
            candidate.activeProfileId = candidate.profiles.empty()
                ? 0
                : candidate.profiles[0].id;
        }
        return true;
    });
}

bool TimbreService::addSchedule(const Schedule& schedule) {
    if (ram_.schedules.full()) {
        return fail(ServiceCode::LimitExceeded, ValidationResult{});
    }
    const ScheduleId id = schedule.id == kInvalidId
        ? nextAvailableScheduleId(ram_)
        : schedule.id;
    if (containsSchedule(ram_, id)) {
        return fail(ServiceCode::DuplicateId, ValidationResult{});
    }
    Schedule copy = schedule;
    copy.id = id;
    const StableIdAllocator savedAllocator = nextScheduleId_;
    const bool committed = transact([&copy](AppState& candidate) {
        if (!candidate.schedules.push_back(copy)) {
            return false;
        }
        return true;
    });
    if (!committed) {
        nextScheduleId_ = savedAllocator;
    }
    return committed;
}

bool TimbreService::updateSchedule(ScheduleId id, const Schedule& schedule) {
    if (!containsSchedule(ram_, id)) {
        return fail(ServiceCode::NotFound, ValidationResult{});
    }
    Schedule copy = schedule;
    copy.id = id;
    return transact([&copy](AppState& candidate) {
        Schedule* target = candidate.schedule(copy.id);
        if (target == nullptr) {
            return false;
        }
        *target = copy;
        return true;
    });
}

bool TimbreService::removeSchedule(ScheduleId id) {
    if (!containsSchedule(ram_, id)) {
        return fail(ServiceCode::NotFound, ValidationResult{});
    }
    return transact([id](AppState& candidate) {
        for (std::size_t i = 0; i < candidate.schedules.size(); ++i) {
            if (candidate.schedules[i].id == id) {
                return candidate.schedules.erase(i);
            }
        }
        return false;
    });
}

bool TimbreService::addHoliday(const Holiday& holiday) {
    if (ram_.holidays.full()) {
        return fail(ServiceCode::LimitExceeded, ValidationResult{});
    }
    const HolidayId id = holiday.id == kInvalidId
        ? nextAvailableHolidayId(ram_)
        : holiday.id;
    if (containsHoliday(ram_, id)) {
        return fail(ServiceCode::DuplicateId, ValidationResult{});
    }
    Holiday copy = holiday;
    copy.id = id;
    const StableIdAllocator savedAllocator = nextHolidayId_;
    const bool committed = transact([&copy](AppState& candidate) {
        if (!candidate.holidays.push_back(copy)) {
            return false;
        }
        return true;
    });
    if (!committed) {
        nextHolidayId_ = savedAllocator;
    }
    return committed;
}

bool TimbreService::updateHoliday(HolidayId id, const Holiday& holiday) {
    if (!containsHoliday(ram_, id)) {
        return fail(ServiceCode::NotFound, ValidationResult{});
    }
    Holiday copy = holiday;
    copy.id = id;
    return transact([&copy](AppState& candidate) {
        Holiday* target = candidate.holiday(copy.id);
        if (target == nullptr) {
            return false;
        }
        *target = copy;
        return true;
    });
}

bool TimbreService::removeHoliday(HolidayId id) {
    if (!containsHoliday(ram_, id)) {
        return fail(ServiceCode::NotFound, ValidationResult{});
    }
    return transact([id](AppState& candidate) {
        for (std::size_t i = 0; i < candidate.holidays.size(); ++i) {
            if (candidate.holidays[i].id == id) {
                return candidate.holidays.erase(i);
            }
        }
        return false;
    });
}

bool TimbreService::setActiveProfile(ProfileId id) {
    if (!containsProfile(ram_, id)) {
        return fail(ServiceCode::NotFound, ValidationResult{});
    }
    return transact([id](AppState& candidate) {
        candidate.activeProfileId = id;
        return true;
    });
}

bool TimbreService::setPattern(PatternId patternIdentifier, const Pattern& pattern) {
    if (!isPatternId(patternIdentifier) ||
        patternIdentifier != pattern.id ||
        !ScheduleValidator::validatePattern(pattern).valid) {
        return fail(ServiceCode::ValidationFailed, ValidationResult{});
    }
    return transact([patternIdentifier, pattern](AppState& candidate) {
        const std::size_t index = patternIndex(patternIdentifier);
        if (index >= candidate.patterns.size()) {
            return false;
        }
        candidate.patterns[index] = pattern;
        return true;
    });
}

bool TimbreService::setPatterns(const std::array<Pattern, kMaxPatterns>& patterns) {
    return transact([&patterns](AppState& candidate) {
        candidate.patterns = patterns;
        return true;
    });
}

} // namespace timbre_core