import { ref, computed, onMounted, onUnmounted } from 'vue';

export function usePetSystem() {
    // --- State ---
    const stage = ref('egg'); // egg, baby, adult
    const state = ref('idle'); // idle, sleep, eating, sick, dead, refuse

    // --- Destiny Data ---
    const DESTINIES = [
        { id: 'luck', name: '福運', description: '籤詩好籤率 +10%', rarity: 1 },
        { id: 'diligence', name: '勤奮', description: '訓練遊戲獎勵 +20%', rarity: 1 },
        { id: 'gluttony', name: '暴食', description: '飢餓下降速度 +30%', rarity: 1 },
        { id: 'playful', name: '愛玩', description: 'Happiness 更快下降／更快上升', rarity: 1 },
        { id: 'purification', name: '淨化', description: '生病機率 -20%', rarity: 1 },
        { id: 'thirdeye', name: '天眼', description: '擲筊出聖筊機率微升', rarity: 2 },
        { id: 'medium', name: '冥感', description: '死亡後招魂成功率提升', rarity: 2 }
    ];

    // --- Stats ---
    const stats = ref({
        hunger: 100,    // 0-100 (0 = Starving)
        happiness: 100, // 0-100 (0 = Depressed)
        health: 100,    // 0-100 (0 = Sick risk)
        weight: 500,    // grams
        age: 1,         // days (start at day 1)
        poopCount: 0,   // Number of poops on screen
        // v2 Stats
        str: 0,         // 力量 (Fireball Game)
        int: 0,         // 智力 (Guessing Game)
        dex: 0,         // 敏捷 (Catch Ball)
        generation: 1,  // 輪迴世代
        deityFavor: 0,  // 神明好感度
        destiny: null   // 天生命格 (Object)
    });

    const achievements = ref([
        { id: 'newbie', name: '新手飼主', desc: '養育超過 1 天', unlocked: false, icon: '🥚' },
        { id: 'veteran', name: '資深飼主', desc: '養育超過 7 天', unlocked: false, icon: '🏆' },
        { id: 'healthy', name: '健康寶寶', desc: '3歲且健康 > 90', unlocked: false, icon: '💪' },
        { id: 'happy', name: '快樂天使', desc: '3歲且快樂 > 90', unlocked: false, icon: '💖' }
    ]);

    // --- Internal Timers ---
    let gameLoopId = null;
    let tickCount = 0;
    const TICK_RATE = 3000; // 3 seconds per tick
    const TICKS_PER_DAY = 20; // For testing: 1 minute = 1 day (usually 28800 for 24h)

    const isCleaning = ref(false);

    // --- Actions ---

    function assignDestiny() {
        // Simple weighted random or just random for now
        // Rarity 2 has lower chance
        const roll = Math.random();
        let pool = DESTINIES;

        // 20% chance for rare destiny
        if (roll < 0.2) {
            pool = DESTINIES.filter(d => d.rarity === 2);
        } else {
            pool = DESTINIES.filter(d => d.rarity === 1);
        }

        const picked = pool[Math.floor(Math.random() * pool.length)];
        stats.value.destiny = picked;
        console.log('Assigned Destiny:', picked);
    }

    function feed() {
        if (state.value === 'sleep' || state.value === 'dead' || stage.value === 'egg' || isCleaning.value) return false;

        if (state.value === 'sick' || stats.value.hunger >= 90) {
            // Refuse food if sick or full
            triggerState('refuse', 2000);
            return false;
        }

        // Eat
        triggerState('eating', 3000); // Animation duration
        stats.value.hunger = Math.min(100, stats.value.hunger + 20);
        stats.value.weight += 50;

        // Chance to poop after eating (降低機率)
        // Destiny Effect: Gluttony (暴食) might increase poop chance? Or just hunger decay.
        if (Math.random() < 0.15) { // 從 0.3 降到 0.15
            setTimeout(() => {
                if (stats.value.poopCount < 4) {
                    stats.value.poopCount++;
                }
            }, 4000);
        }

        return true;
    }

    function play() {
        if (state.value !== 'idle' || stage.value === 'egg' || isCleaning.value) return false;

        stats.value.happiness = Math.min(100, stats.value.happiness + 15);
        stats.value.weight -= 10; // Exercise burns calories
        stats.value.hunger = Math.max(0, stats.value.hunger - 5);
        return true;
    }

    function clean() {
        if (stats.value.poopCount > 0 && !isCleaning.value) {
            isCleaning.value = true;

            // Delay removal for animation
            setTimeout(() => {
                stats.value.poopCount = 0;
                stats.value.happiness += 10;
                isCleaning.value = false;
            }, 2000); // 2 seconds flush animation

            return true;
        }
        return false;
    }

    function sleep() {
        if (isCleaning.value) return;

        if (state.value === 'idle') {
            state.value = 'sleep';
        } else if (state.value === 'sleep') {
            state.value = 'idle'; // Wake up
        }
    }

    // --- Game Loop ---
    function tick() {
        if (state.value === 'dead' || stage.value === 'egg') return;

        // Decrease stats naturally
        // Destiny Effect: Gluttony (暴食) - Hunger decreases faster (+30%)
        let hungerDecay = 0.05;
        if (stats.value.destiny?.id === 'gluttony') {
            hungerDecay *= 1.3;
        }

        // Destiny Effect: Playful (愛玩) - Happiness decreases faster
        let happinessDecay = 0.08;
        if (stats.value.destiny?.id === 'playful') {
            happinessDecay *= 1.2; // Faster decay
        }

        // Destiny Effect: DEX (敏捷) - Hunger decreases slower
        // DEX 10 = -10% decay, DEX 50 = -50% decay
        if (stats.value.dex > 0) {
            const reduction = Math.min(0.5, stats.value.dex * 0.01); // Max 50% reduction
            hungerDecay *= (1 - reduction);
        }

        if (state.value !== 'sleep') {
            stats.value.hunger = Math.max(0, stats.value.hunger - hungerDecay);
            stats.value.happiness = Math.max(0, stats.value.happiness - happinessDecay);
        } else {
            // Slower decay when sleeping (約 1/3 速度)
            stats.value.hunger = Math.max(0, stats.value.hunger - (hungerDecay * 0.3));
            stats.value.happiness = Math.max(0, stats.value.happiness - (happinessDecay * 0.3));
        }

        // Random poop generation (更低的機率：約 0.5% per tick)
        // 平均約每 200 ticks = 10 分鐘拉一次
        if (state.value !== 'sleep' && Math.random() < 0.005 && stats.value.poopCount < 4 && !isCleaning.value) {
            stats.value.poopCount++;
        }

        // Health Logic (更溫和的健康下降)
        // 便便影響健康：每個便便每 tick -0.1 health
        if (stats.value.poopCount > 0) {
            stats.value.health = Math.max(0, stats.value.health - (0.1 * stats.value.poopCount));
        }

        // 飢餓影響健康：飢餓值低於 20 時開始影響健康
        if (stats.value.hunger < 20) {
            const hungerPenalty = (20 - stats.value.hunger) * 0.02; // 飢餓越嚴重，扣越多
            stats.value.health = Math.max(0, stats.value.health - hungerPenalty);
        }

        // 不開心影響健康：快樂值低於 20 時開始影響健康（較輕微）
        if (stats.value.happiness < 20) {
            const happinessPenalty = (20 - stats.value.happiness) * 0.01;
            stats.value.health = Math.max(0, stats.value.health - happinessPenalty);
        }

        // Sickness Check (更低的生病機率)
        // Destiny Effect: Purification (淨化) - Sickness chance -20%
        let sickChance = 0.1;
        if (stats.value.destiny?.id === 'purification') {
            sickChance *= 0.8;
        }

        if (stats.value.health < 30 && state.value !== 'sick') {
            if (Math.random() < sickChance) {
                state.value = 'sick';
            }
        }

        // Health Recovery (健康值可以緩慢恢復)
        // 如果沒有便便、飢餓值和快樂值都高，健康值會緩慢恢復
        if (stats.value.poopCount === 0 && stats.value.hunger > 50 && stats.value.happiness > 50 && stats.value.health < 100 && state.value !== 'sick') {
            stats.value.health = Math.min(100, stats.value.health + 0.05);
        }

        // Death Check (移除死亡機制，依照之前的討論)
        // if (stats.value.health === 0) {
        //     state.value = 'dead';
        // }

        // Evolution / Growth
        tickCount++;
        if (tickCount >= TICKS_PER_DAY) {
            stats.value.age++;
            tickCount = 0;
            checkEvolution();
        }

        checkAchievements();
    }

    function checkAchievements() {
        if (!achievements.value[0].unlocked && stats.value.age >= 1) {
            unlockAchievement(0);
        }
        if (!achievements.value[1].unlocked && stats.value.age >= 7) {
            unlockAchievement(1);
        }
        if (!achievements.value[2].unlocked && stats.value.age >= 3 && stats.value.health >= 90) {
            unlockAchievement(2);
        }
        if (!achievements.value[3].unlocked && stats.value.age >= 3 && stats.value.happiness >= 90) {
            unlockAchievement(3);
        }
    }

    function unlockAchievement(index) {
        if (!achievements.value[index].unlocked) {
            achievements.value[index].unlocked = true;
            triggerState('happy', 2000); // Celebrate achievement
        }
    }

    function unlockAllAchievements() {
        achievements.value.forEach(a => a.unlocked = true);
        triggerState('happy', 2000);
    }

    function checkEvolution() {
        // Simple evolution logic
        if (stage.value === 'baby' && stats.value.age >= 3) {
            stage.value = 'child';
            triggerState('happy', 2000); // Celebrate
        } else if (stage.value === 'child' && stats.value.age >= 7) {
            stage.value = 'adult';
            triggerState('happy', 2000);
        }
    }

    // --- Helpers ---
    function triggerState(tempState, duration) {
        const previousState = state.value;
        state.value = tempState;
        setTimeout(() => {
            if (state.value === tempState) { // Only revert if state hasn't changed again
                state.value = previousState === 'sleep' ? 'idle' : 'idle';
            }
        }, duration);
    }

    function hatchEgg() {
        if (stage.value === 'egg') {
            stage.value = 'baby'; // or 'adult' for now since we only have that sprite
            // Let's map 'baby' to our 'adult' sprite for now, or just use 'adult'
            stage.value = 'adult';
            state.value = 'idle';
            stats.value.hunger = 50;
            stats.value.happiness = 50;
            stats.value.health = 100;
            stats.value.poopCount = 0;

            // v2: Assign Destiny
            assignDestiny();

            isCleaning.value = false;
        }
    }

    function reset() {
        stage.value = 'egg';
        state.value = 'idle';
        isCleaning.value = false;
        stats.value = {
            hunger: 100,
            happiness: 100,
            health: 100,
            weight: 500,
            age: 1,
            poopCount: 0,
            // v2 Reset
            str: 0,
            int: 0,
            dex: 0,
            generation: 1,
            deityFavor: 0,
            destiny: null
        };
        tickCount = 0;
    }

    function resurrect() {
        if (state.value !== 'dead') return;

        state.value = 'idle';
        stats.value.health = 50; // Revive with half health
        stats.value.happiness = 50;
        stats.value.hunger = 50;

        // Penalty or Ghost Buff?
        // For now just a console log, maybe visual effect later
        console.log('Pet Resurrected!');
    }

    function reincarnate() {
        // Inherit logic
        const prevDestiny = stats.value.destiny;
        const prevFavor = stats.value.deityFavor;
        const nextGen = (stats.value.generation || 1) + 1;

        // Reset everything
        reset();

        // Apply Inheritance
        stats.value.generation = nextGen;

        // 20% Favor inheritance
        stats.value.deityFavor = Math.floor(prevFavor * 0.2);

        // Destiny Inheritance (Optional: Maybe keep if it was a rare one?)
        // For now, let's say if you had a Rare (2) destiny, you keep it.
        // Otherwise, you get a new one on hatch.
        if (prevDestiny && prevDestiny.rarity === 2) {
            stats.value.destiny = prevDestiny;
        }

        console.log('Pet Reincarnated to Gen', nextGen);
    }

    // --- Lifecycle ---
    onMounted(() => {
        gameLoopId = setInterval(tick, TICK_RATE);
    });

    onUnmounted(() => {
        if (gameLoopId) clearInterval(gameLoopId);
    });

    return {
        stage,
        state,
        stats,
        isCleaning,
        feed,
        play,
        clean,
        sleep,
        hatchEgg,
        reset,
        achievements,
        unlockAllAchievements,
        assignDestiny, // Export for debug if needed
        resurrect,
        reincarnate
    };
}