function saveToHistory(title) {
    if(!title) {
        title = document.getElementById('query').value.slice(0, 10);
    }
    const historyItem = {
        query: document.getElementById('query').value,
        promptEn: document.getElementById('promptEn').value,
        promptMyLanguage: document.getElementById('promptMyLanguage').value,
        danbooruTags: document.getElementById('danbooruTags').value,
        timestamp: new Date().toISOString(),
        title: title
    };

    let history = JSON.parse(localStorage.getItem('gemini_prompt_history') || '[]');
    history.unshift(historyItem);
    // 履歴の合計サイズが3MB以下になるまで古い項目を削除
    while (JSON.stringify(history).length > 3 * 1024 * 1024) {
        history.pop();
    }
    localStorage.setItem('gemini_prompt_history', JSON.stringify(history));

    updateHistoryList();
}
function updateHistoryList() {
    const historyList = document.getElementById('historyList');
    const noHistoryMessage = document.getElementById('noHistoryMessage');
    historyList.innerHTML = '';

    const history = JSON.parse(localStorage.getItem('gemini_prompt_history') || '[]');

    if (history.length === 0) {
        noHistoryMessage.classList.remove('d-none');
        historyList.classList.add('d-none');
    } else {
        noHistoryMessage.classList.add('d-none');
        historyList.classList.remove('d-none');

        history.forEach((item, index) => {
            const li = document.createElement('li');
            li.className = 'list-group-item list-group-item-action d-flex justify-content-between align-items-start';

            const contentDiv = document.createElement('div');
            contentDiv.className = 'ms-2 me-auto';
            contentDiv.style.cursor = 'pointer';
            contentDiv.onclick = () => loadHistoryItem(index);

            const titleDiv = document.createElement('div');
            titleDiv.className = 'fw-bold text-truncate';
            titleDiv.textContent = item.title || item.query.slice(0, 10);

            const dateDiv = document.createElement('div');
            dateDiv.className = 'small text-muted';
            dateDiv.textContent = new Date(item.timestamp).toLocaleString();

            contentDiv.appendChild(titleDiv);
            contentDiv.appendChild(dateDiv);

            const buttonsContainer = document.createElement('div');
            buttonsContainer.className = 'd-flex';

            const editButton = document.createElement('button');
            editButton.className = 'btn btn-secondary btn-sm me-2';
            editButton.innerHTML = '<i class="fas fa-pencil-alt"></i>';
            editButton.onclick = (e) => {
                e.stopPropagation();
                editHistoryItemTitle(index, titleDiv);
            };

            const deleteButton = document.createElement('button');
            deleteButton.className = 'btn btn-danger btn-sm';
            deleteButton.innerHTML = '<i class="fas fa-trash"></i>';
            deleteButton.onclick = (e) => {
                e.stopPropagation();
                deleteHistoryItem(index);
            };

            buttonsContainer.appendChild(editButton);
            buttonsContainer.appendChild(deleteButton);

            li.appendChild(contentDiv);
            li.appendChild(buttonsContainer);
            historyList.appendChild(li);

            contentDiv.style.width = `calc(100% - ${buttonsContainer.offsetWidth}px)`;
        });
    }
}
function deleteHistoryItem(index) {
    if (confirm('この履歴項目を削除してもよろしいですか？')) {
        let history = JSON.parse(localStorage.getItem('gemini_prompt_history') || '[]');
        history.splice(index, 1);
        localStorage.setItem('gemini_prompt_history', JSON.stringify(history));
        updateHistoryList();
    }
}
function loadHistoryItem(index) {
    const history = JSON.parse(localStorage.getItem('gemini_prompt_history') || '[]');
    const item = history[index];

    document.getElementById('query').value = item.query;
    document.getElementById('promptEn').value = item.promptEn;
    document.getElementById('promptMyLanguage').value = item.promptMyLanguage;
    document.getElementById('danbooruTags').value = item.danbooruTags;

    saveToUserStorage(true);
}

function clearHistory() {
    if (confirm('本当に履歴をすべて削除してもよろしいですか？')) {
        localStorage.removeItem('gemini_prompt_history');
        updateHistoryList();
    }
}

function createHistoryItem(item, index) {
    const li = document.createElement('li');
    li.className = 'list-group-item d-flex justify-content-between align-items-center';

    const titleSpan = document.createElement('span');
    titleSpan.textContent = item.title || item.query.slice(0, 10);
    titleSpan.className = 'me-2';
    li.appendChild(titleSpan);

    const buttonsContainer = document.createElement('div');

    const editButton = document.createElement('button');
    editButton.className = 'btn btn-sm btn-secondary me-2';
    editButton.innerHTML = '<i class="fas fa-pencil-alt"></i>';
    editButton.onclick = () => editHistoryItemTitle(index, titleSpan);

    const useButton = document.createElement('button');
    useButton.className = 'btn btn-sm btn-primary me-2';
    useButton.innerHTML = '<i class="fas fa-redo"></i>';
    useButton.onclick = () => useHistoryItem(index);

    const deleteButton = document.createElement('button');
    deleteButton.className = 'btn btn-sm btn-danger';
    deleteButton.innerHTML = '<i class="fas fa-trash"></i>';
    deleteButton.onclick = () => {
        if (confirm('この履歴項目を削除してもよろしいですか？')) {
            deleteHistoryItem(index);
        }
    };

    buttonsContainer.appendChild(editButton);
    buttonsContainer.appendChild(useButton);
    buttonsContainer.appendChild(deleteButton);
    li.appendChild(buttonsContainer);

    return li;
}

function editHistoryItemTitle(index, titleDiv) {
    const history = JSON.parse(localStorage.getItem('gemini_prompt_history') || '[]');
    const item = history[index];
    const currentTitle = item.title || item.query.slice(0, 10);

    const newTitle = prompt('新しいタイトルを入力してください:', currentTitle);
    if (newTitle !== null && newTitle.trim() !== '') {
        item.title = newTitle.trim();
        history[index] = item;
        localStorage.setItem('gemini_prompt_history', JSON.stringify(history));
        titleDiv.textContent = newTitle.trim();
    }
}