/**
 * Storage reads and writes the browser's local cache and the saved
 * client settings. It is the only module that touches localStorage.
 * It does no rendering and sends no requests: main.js decides what
 * to cache and when, and Storage only stores and returns it.
 *
 * Keys and their contents:
 * - odidere_conversation: the selected conversation ID and its saved
 *   message rows, for offline viewing and a fast start. The server
 *   owns the history; this entry is a copy, replaced by every sync.
 * - odidere_system_message: the system message used when the next
 *   conversation is created. It does not change a conversation that
 *   already exists.
 * - odidere_provider, odidere_model, odidere_voice: selections.
 * - odidere_max_turns, odidere_reasoning_budget: compose settings.
 * - odidere_mute: whether speech playback is muted.
 *
 * The browser-only history that older versions kept under
 * odidere_history is not read and is left untouched.
 */

const CONVERSATION_KEY = 'odidere_conversation';
const SYSTEM_MESSAGE_KEY = 'odidere_system_message';
const PROVIDER_KEY = 'odidere_provider';
const MODEL_KEY = 'odidere_model';
const VOICE_KEY = 'odidere_voice';
const MAX_TURNS_KEY = 'odidere_max_turns';
const REASONING_BUDGET_KEY = 'odidere_reasoning_budget';
const MUTE_KEY = 'odidere_mute';

export class Storage {
  /**
   * loadConversation returns the cached selection: the conversation
   * ID and its message rows in saved order. Rows are stored under
   * their message IDs; the array order is the saved order.
   * @returns {{id: string, rows: Array<Object>} | null}
   */
  loadConversation() {
    try {
      const cached = JSON.parse(localStorage.getItem(CONVERSATION_KEY));
      if (!cached?.id || !Array.isArray(cached.rows)) return null;
      return { id: cached.id, rows: cached.rows };
    } catch (error) {
      console.error('failed to load conversation cache:', error);
      return null;
    }
  }

  /**
   * saveConversation caches the selected conversation and its rows.
   * The server owns the history; this is a local copy for offline
   * viewing. Streaming drafts are never passed to this method.
   * @param {string} id
   * @param {Array<Object>} rows
   */
  saveConversation(id, rows) {
    try {
      localStorage.setItem(CONVERSATION_KEY, JSON.stringify({ id, rows }));
    } catch (error) {
      console.error('failed to cache conversation:', error);
    }
  }

  /**
   * clearConversation drops the cached selection. It does not
   * change or delete the conversation on the server.
   */
  clearConversation() {
    try {
      localStorage.removeItem(CONVERSATION_KEY);
    } catch (error) {
      console.error('failed to clear conversation cache:', error);
    }
  }

  // --- System message ---

  /** @returns {string} the saved default system message, or '' */
  getSystemMessage() {
    return localStorage.getItem(SYSTEM_MESSAGE_KEY) || '';
  }

  /**
   * setSystemMessage stores the default system message for the next
   * conversation. It does not change any existing conversation.
   * @param {string} value
   */
  setSystemMessage(value) {
    localStorage.setItem(SYSTEM_MESSAGE_KEY, value);
  }

  // --- Model and voice ---

  /** @returns {{provider: string | null, model: string | null}} */
  getModelSelection() {
    return {
      provider: localStorage.getItem(PROVIDER_KEY),
      model: localStorage.getItem(MODEL_KEY),
    };
  }

  /**
   * setModelSelection stores the selected provider and model.
   * @param {{provider: string, model: string}} selection
   */
  setModelSelection({ provider, model }) {
    localStorage.setItem(PROVIDER_KEY, provider);
    localStorage.setItem(MODEL_KEY, model);
  }

  /** @returns {string} the selected voice, or '' for automatic */
  getVoice() {
    return localStorage.getItem(VOICE_KEY) || '';
  }

  /**
   * setVoice stores the selected voice. '' selects the default.
   * @param {string} voice
   */
  setVoice(voice) {
    localStorage.setItem(VOICE_KEY, voice);
  }

  // --- Compose settings ---

  /**
   * getMaxIterations returns the agent loop limit. Zero means no
   * limit: the model replies without tool calls or the run fails.
   * @returns {number}
   */
  getMaxIterations() {
    const stored = Number(localStorage.getItem(MAX_TURNS_KEY));
    return Number.isFinite(stored) && stored > 0 ? stored : 0;
  }

  /**
   * setMaxIterations stores the agent loop limit. Zero means no
   * limit.
   * @param {number} value
   */
  setMaxIterations(value) {
    localStorage.setItem(MAX_TURNS_KEY, String(value));
  }

  /**
   * getReasoningBudget returns the llama.cpp reasoning token budget,
   * or null when unset. -1 means unlimited and 0 means off.
   * @returns {number | null}
   */
  getReasoningBudget() {
    const stored = localStorage.getItem(REASONING_BUDGET_KEY);
    if (stored === null) return null;
    const value = Number(stored);
    return Number.isFinite(value) ? value : null;
  }

  /**
   * setReasoningBudget stores the reasoning token budget. null
   * removes the setting and leaves the choice to the server.
   * @param {number | null} value
   */
  setReasoningBudget(value) {
    if (value === null) {
      localStorage.removeItem(REASONING_BUDGET_KEY);
    } else {
      localStorage.setItem(REASONING_BUDGET_KEY, String(value));
    }
  }

  // --- Mute ---

  /** @returns {boolean} whether speech playback is muted */
  getMuted() {
    return localStorage.getItem(MUTE_KEY) === 'true';
  }

  /**
   * setMuted stores the speech mute state.
   * @param {boolean} muted
   */
  setMuted(muted) {
    localStorage.setItem(MUTE_KEY, String(muted));
  }
}