import { Injectable, signal, computed } from '@angular/core';

/**
 * Search preferences per context
 */
export interface SearchPreferences {
  /** Case sensitive search */
  caseSensitive: boolean;
  /** Regex mode enabled */
  regexMode: boolean;
  /** Collapse all results by default */
  collapseResults: boolean;
  /** Show more context around matches */
  showMoreContext: boolean;
  /** Number of context lines (when showMoreContext is true) */
  contextLines: number;
  /** Explain search terms */
  explainSearchTerms: boolean;
}

/**
 * Default preferences
 */
const DEFAULT_PREFERENCES: SearchPreferences = {
  caseSensitive: false,
  regexMode: false,
  collapseResults: false,
  showMoreContext: false,
  contextLines: 2,
  explainSearchTerms: false
};

/**
 * Search preferences service
 * Manages persistent search preferences per context (vault, header, graph)
 */
@Injectable({
  providedIn: 'root'
})
export class SearchPreferencesService {
  private readonly STORAGE_KEY = 'obsiviewer_search_preferences';

  // Preferences by context
  private preferencesMap = signal<Map<string, SearchPreferences>>(new Map());

  constructor() {
    this.loadFromStorage();
  }

  /**
   * Get preferences for a specific context
   */
  getPreferences(context: string = 'vault'): SearchPreferences {
    const prefs = this.preferencesMap().get(context);
    return prefs ? { ...prefs } : { ...DEFAULT_PREFERENCES };
  }

  /**
   * Get preferences signal for a specific context
   */
  getPreferencesSignal(context: string = 'vault') {
    return computed(() => {
      const prefs = this.preferencesMap().get(context);
      return prefs ? { ...prefs } : { ...DEFAULT_PREFERENCES };
    });
  }

  /**
   * Update preferences for a specific context
   */
  updatePreferences(context: string, updates: Partial<SearchPreferences>): void {
    this.preferencesMap.update(map => {
      const current = map.get(context) || { ...DEFAULT_PREFERENCES };
      const updated = { ...current, ...updates };
      map.set(context, updated);
      return new Map(map);
    });

    this.saveToStorage();
  }

  /**
   * Toggle a boolean preference
   */
  togglePreference(
    context: string,
    key: keyof Pick<SearchPreferences, 'caseSensitive' | 'regexMode' | 'collapseResults' | 'showMoreContext' | 'explainSearchTerms'>
  ): void {
    const current = this.getPreferences(context);
    this.updatePreferences(context, {
      [key]: !current[key]
    });
  }

  /**
   * Set context lines
   */
  setContextLines(context: string, lines: number): void {
    this.updatePreferences(context, { contextLines: Math.max(0, Math.min(10, lines)) });
  }

  /**
   * Reset preferences for a context
   */
  resetPreferences(context: string): void {
    this.preferencesMap.update(map => {
      map.set(context, { ...DEFAULT_PREFERENCES });
      return new Map(map);
    });

    this.saveToStorage();
  }

  /**
   * Reset all preferences
   */
  resetAllPreferences(): void {
    this.preferencesMap.set(new Map());
    this.saveToStorage();
  }

  /**
   * Load preferences from localStorage
   */
  private loadFromStorage(): void {
    try {
      const stored = localStorage.getItem(this.STORAGE_KEY);
      if (stored) {
        const data = JSON.parse(stored);
        const map = new Map<string, SearchPreferences>();
        
        for (const [context, prefs] of Object.entries(data)) {
          map.set(context, { ...DEFAULT_PREFERENCES, ...(prefs as any) });
        }
        
        this.preferencesMap.set(map);
      }
    } catch (e) {
      console.error('Failed to load search preferences:', e);
    }
  }

  /**
   * Save preferences to localStorage
   */
  private saveToStorage(): void {
    try {
      const data: Record<string, SearchPreferences> = {};
      
      this.preferencesMap().forEach((prefs, context) => {
        data[context] = prefs;
      });
      
      localStorage.setItem(this.STORAGE_KEY, JSON.stringify(data));
    } catch (e) {
      console.error('Failed to save search preferences:', e);
    }
  }

  /**
   * Export preferences as JSON
   */
  exportPreferences(): string {
    const data: Record<string, SearchPreferences> = {};
    
    this.preferencesMap().forEach((prefs, context) => {
      data[context] = prefs;
    });
    
    return JSON.stringify(data, null, 2);
  }

  /**
   * Import preferences from JSON
   */
  importPreferences(json: string): boolean {
    try {
      const data = JSON.parse(json);
      const map = new Map<string, SearchPreferences>();
      
      for (const [context, prefs] of Object.entries(data)) {
        map.set(context, { ...DEFAULT_PREFERENCES, ...(prefs as any) });
      }
      
      this.preferencesMap.set(map);
      this.saveToStorage();
      return true;
    } catch (e) {
      console.error('Failed to import search preferences:', e);
      return false;
    }
  }
}