import { Component, ChangeDetectionStrategy, inject, signal, computed, effect, ElementRef, OnDestroy } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';

// Services
import { VaultService } from './services/vault.service';
import { MarkdownService } from './services/markdown.service';

// Components
import { FileExplorerComponent } from './components/file-explorer/file-explorer.component';
import { NoteViewerComponent } from './components/note-viewer/note-viewer.component';
import { GraphViewComponent } from './components/graph-view/graph-view.component';
import { TagsViewComponent } from './components/tags-view/tags-view.component';
import { MarkdownCalendarComponent } from './components/markdown-calendar/markdown-calendar.component';

// Types
import { FileMetadata, Note, TagInfo, VaultNode } from './types';

interface TocEntry {
  level: number;
  text: string;
  id: string;
}

@Component({
  selector: 'app-root',
  imports: [
    CommonModule,
    FormsModule,
    FileExplorerComponent,
    NoteViewerComponent,
    GraphViewComponent,
    TagsViewComponent,
    MarkdownCalendarComponent,
  ],
  templateUrl: './app.component.simple.html',
  styleUrls: ['./app.component.css'],
  changeDetection: ChangeDetectionStrategy.OnPush,
})
export class AppComponent implements OnDestroy {
  private vaultService = inject(VaultService);
  private markdownService = inject(MarkdownService);
  private elementRef = inject(ElementRef);

  // --- State Signals ---
  isDarkMode = signal<boolean>(true);
  isSidebarOpen = signal<boolean>(true);
  isOutlineOpen = signal<boolean>(true);
  activeView = signal<'files' | 'graph' | 'tags' | 'search' | 'calendar'>('files');
  selectedNoteId = signal<string>('');
  sidebarSearchTerm = signal<string>('');
  tableOfContents = signal<TocEntry[]>([]);
  leftSidebarWidth = signal<number>(288);
  rightSidebarWidth = signal<number>(288);
  readonly LEFT_MIN_WIDTH = 220;
  readonly LEFT_MAX_WIDTH = 520;
  readonly RIGHT_MIN_WIDTH = 220;
  readonly RIGHT_MAX_WIDTH = 520;

  private viewportWidth = signal<number>(typeof window !== 'undefined' ? window.innerWidth : 0);
  private resizeHandler = () => {
    if (typeof window === 'undefined') {
      return;
    }
    this.viewportWidth.set(window.innerWidth);
  };

  isDesktopView = computed<boolean>(() => this.viewportWidth() >= 1024);
  private wasDesktop = false;

  calendarResults = signal<FileMetadata[]>([]);
  calendarSearchState = signal<'idle' | 'loading' | 'error'>('idle');
  calendarSearchError = signal<string | null>(null);
  calendarSelectionLabel = signal<string | null>(null);
  calendarOverlayVisible = computed<boolean>(() =>
    this.calendarSearchState() === 'loading' ||
    !!this.calendarSearchError() ||
    this.calendarResults().length > 0
  );
  private calendarSearchTriggered = false;

  // --- Data Signals ---
  fileTree = this.vaultService.fileTree;
  graphData = this.vaultService.graphData;
  allTags = this.vaultService.tags;
  vaultName = this.vaultService.vaultName;

  // --- Computed Signals ---
  selectedNote = computed<Note | undefined>(() => {
    const id = this.selectedNoteId();
    return id ? this.vaultService.getNoteById(id) : undefined;
  });

  renderedNoteContent = computed<string>(() => {
    const note = this.selectedNote();
    if (!note) return '';
    const allNotes = this.vaultService.allNotes();
    return this.markdownService.render(note.content, allNotes, note);
  });

  selectedNoteBreadcrumb = computed<string[]>(() => {
    const note = this.selectedNote();
    if (!note) {
      return [];
    }

    const vaultTitle = this.vaultName().trim();
    const breadcrumb: string[] = [vaultTitle || 'Vault'];
    const pathSegments = note.originalPath.split('/').filter(Boolean);

    if (pathSegments.length === 0) {
      breadcrumb.push(note.fileName.replace(/\.md$/i, '')); 
      return breadcrumb;
    }

    const displaySegments = [...pathSegments];
    displaySegments[displaySegments.length - 1] = note.fileName.replace(/\.md$/i, '');
    return breadcrumb.concat(displaySegments);
  });

  filteredTags = computed<TagInfo[]>(() => {
    const term = this.sidebarSearchTerm().trim().toLowerCase();
    const cleanedTerm = term.startsWith('#') ? term.slice(1) : term;
    if (!cleanedTerm) return this.allTags();
    return this.allTags().filter(tag => tag.name.toLowerCase().includes(cleanedTerm));
  });

  filteredFileTree = computed<VaultNode[]>(() => {
    const term = this.sidebarSearchTerm().trim().toLowerCase();
    if (!term || term.startsWith('#')) return this.fileTree();
    // Simple flat search for files
    return this.fileTree().filter(node => node.type === 'file' && node.name.toLowerCase().includes(term));
  });

  activeTagFilter = computed<string | null>(() => {
    const rawTerm = this.sidebarSearchTerm().trim();
    if (!rawTerm.startsWith('#')) {
      return null;
    }

    const tag = rawTerm.slice(1).trim();
    return tag ? tag.toLowerCase() : null;
  });
  
  searchResults = computed<Note[]>(() => {
    const notes = this.vaultService.allNotes();
    const tagFilter = this.activeTagFilter();

    if (tagFilter) {
      return notes.filter(note => note.tags.some(tag => tag.toLowerCase() === tagFilter));
    }

    const term = this.sidebarSearchTerm().trim().toLowerCase();
    if (!term) return [];
    const cleanedTerm = term.startsWith('#') ? term.slice(1) : term;
    return notes.filter(note => 
      note.title.toLowerCase().includes(cleanedTerm) || 
      note.content.toLowerCase().includes(cleanedTerm) ||
      note.tags.some(tag => tag.toLowerCase().includes(cleanedTerm))
    );
  });

  constructor() {
    if (typeof window !== 'undefined') {
      window.addEventListener('resize', this.resizeHandler, { passive: true });
    }

    this.wasDesktop = this.isDesktopView();
    if (!this.isDesktopView()) {
      this.isSidebarOpen.set(false);
      this.isOutlineOpen.set(false);
    }

    // Effect to update the DOM with the dark class
    effect(() => {
      if (this.isDarkMode()) {
        document.documentElement.classList.add('dark');
      } else {
        document.documentElement.classList.remove('dark');
      }
    });

    effect(() => {
      const isDesktop = this.isDesktopView();
      if (isDesktop && !this.wasDesktop) {
        this.isSidebarOpen.set(true);
        this.isOutlineOpen.set(true);
      }
      if (!isDesktop && this.wasDesktop) {
        this.isSidebarOpen.set(false);
        this.isOutlineOpen.set(false);
      }
      this.wasDesktop = isDesktop;
    });

    // Effect to generate Table of Contents when the note changes
    effect(() => {
      const html = this.renderedNoteContent();
      if (html && this.selectedNote()) {
        this.generateToc(html);
      } else {
        this.tableOfContents.set([]);
      }
    });

    effect(() => {
      if (typeof document === 'undefined') {
        return;
      }
      const vaultTitle = this.vaultName().trim();
      document.title = `ObsiWatcher - ${vaultTitle || 'Vault'}`;
    });

    // Effect to select first available note when vault data loads
    effect(() => {
      const notes = this.vaultService.allNotes();
      const currentId = this.selectedNoteId();
      if (!notes.length) {
        return;
      }

      const currentExists = notes.some(note => note.id === currentId);
      if (!currentExists) {
        const firstNote = notes[0];
        this.vaultService.ensureFolderOpen(firstNote.originalPath);
        this.selectedNoteId.set(firstNote.id);
      }
    });
  }

  ngOnDestroy(): void {
    if (typeof window !== 'undefined') {
      window.removeEventListener('resize', this.resizeHandler);
    }
  }

  // --- Methods ---
  toggleTheme(): void {
    this.isDarkMode.update(value => !value);
  }

  toggleSidebar(): void {
    this.isSidebarOpen.update(value => !value);
  }

  closeSidebar(): void {
    this.isSidebarOpen.set(false);
  }

  toggleSidebarTo(state: boolean): void {
    this.isSidebarOpen.set(state);
  }

  toggleOutline(): void {
    this.isOutlineOpen.update(value => !value);
  }

  closeOutlinePanel(): void {
    this.isOutlineOpen.set(false);
  }

  toggleOutlineTo(state: boolean): void {
    this.isOutlineOpen.set(state);
  }

  isDesktop(): boolean {
    return this.isDesktopView();
  }

  onCalendarResultsChange(files: FileMetadata[]): void {
    this.calendarResults.set(files);
    if (this.calendarSearchTriggered || files.length > 0 || this.activeView() === 'search') {
      this.isSidebarOpen.set(true);
      this.activeView.set('search');
      this.calendarSearchTriggered = false;
    }
  }

  onCalendarSearchStateChange(state: 'idle' | 'loading' | 'error'): void {
    this.calendarSearchState.set(state);
    if (state === 'loading') {
      this.calendarSearchTriggered = true;
    }
  }

  onCalendarSearchErrorChange(message: string | null): void {
    this.calendarSearchError.set(message);
    if (message) {
      this.isSidebarOpen.set(true);
      this.activeView.set('search');
      this.calendarSearchTriggered = false;
    }
  }

  onCalendarSelectionSummaryChange(summary: string | null): void {
    this.calendarSelectionLabel.set(summary);
  }

  onCalendarRequestSearchPanel(): void {
    if (this.activeView() === 'calendar') {
      if (!this.isSidebarOpen()) {
        this.isSidebarOpen.set(true);
      }
      return;
    }
    this.isSidebarOpen.set(true);
    this.activeView.set('search');
  }

  startLeftResize(event: PointerEvent): void {
    if (!this.isSidebarOpen()) {
      this.isSidebarOpen.set(true);
    }

    event.preventDefault();
    const handle = event.currentTarget as HTMLElement | null;
    handle?.setPointerCapture(event.pointerId);

    const startX = event.clientX;
    const startWidth = this.leftSidebarWidth();

    const moveHandler = (moveEvent: PointerEvent) => {
      const delta = moveEvent.clientX - startX;
      let newWidth = startWidth + delta;
      newWidth = Math.max(this.LEFT_MIN_WIDTH, Math.min(this.LEFT_MAX_WIDTH, newWidth));
      this.leftSidebarWidth.set(newWidth);
    };

    const cleanup = () => {
      window.removeEventListener('pointermove', moveHandler);
      window.removeEventListener('pointerup', cleanup);
      window.removeEventListener('pointercancel', cleanup);
      if (handle && handle.hasPointerCapture?.(event.pointerId)) {
        handle.releasePointerCapture(event.pointerId);
      }
      handle?.removeEventListener('lostpointercapture', cleanup);
    };

    window.addEventListener('pointermove', moveHandler);
    window.addEventListener('pointerup', cleanup);
    window.addEventListener('pointercancel', cleanup);
    handle?.addEventListener('lostpointercapture', cleanup);
  }

  startRightResize(event: PointerEvent): void {
    if (!this.isOutlineOpen()) {
      this.isOutlineOpen.set(true);
    }

    event.preventDefault();
    const handle = event.currentTarget as HTMLElement | null;
    handle?.setPointerCapture(event.pointerId);

    const startX = event.clientX;
    const startWidth = this.rightSidebarWidth();

    const moveHandler = (moveEvent: PointerEvent) => {
      const delta = moveEvent.clientX - startX;
      let newWidth = startWidth - delta;
      newWidth = Math.max(this.RIGHT_MIN_WIDTH, Math.min(this.RIGHT_MAX_WIDTH, newWidth));
      this.rightSidebarWidth.set(newWidth);
    };

    const cleanup = () => {
      window.removeEventListener('pointermove', moveHandler);
      window.removeEventListener('pointerup', cleanup);
      window.removeEventListener('pointercancel', cleanup);
      if (handle && handle.hasPointerCapture?.(event.pointerId)) {
        handle.releasePointerCapture(event.pointerId);
      }
      handle?.removeEventListener('lostpointercapture', cleanup);
    };

    window.addEventListener('pointermove', moveHandler);
    window.addEventListener('pointerup', cleanup);
    window.addEventListener('pointercancel', cleanup);
    handle?.addEventListener('lostpointercapture', cleanup);
  }

  setView(view: 'files' | 'graph' | 'tags' | 'search' | 'calendar'): void {
    this.activeView.set(view);
    this.sidebarSearchTerm.set('');
  }

  selectNote(noteId: string): void {
    const note = this.vaultService.getNoteById(noteId);
    if (!note) {
      return;
    }

    this.vaultService.ensureFolderOpen(note.originalPath);
    this.selectedNoteId.set(note.id);

    if (!this.isDesktopView() && this.activeView() === 'search') {
      this.isSidebarOpen.set(false);
    }
  }
  
  handleTagClick(tagName: string): void {
    const normalized = tagName.replace(/^#/, '').trim();
    if (!normalized) {
      return;
    }
    this.setView('search');
    this.sidebarSearchTerm.set(`#${normalized}`);
  }

  clearTagFilter(): void {
    this.sidebarSearchTerm.set('');
  }

  clearCalendarResults(): void {
    this.calendarResults.set([]);
    this.calendarSearchState.set('idle');
    this.calendarSearchError.set(null);
    this.calendarSelectionLabel.set(null);
    this.calendarSearchTriggered = false;
  }

  updateSearchTerm(term: string, focusSearch = false): void {
    this.sidebarSearchTerm.set(term ?? '');
    if (focusSearch || (term && term.trim().length > 0)) {
      this.activeView.set('search');
    }
  }

  private generateToc(html: string): void {
    const toc: TocEntry[] = [];
    const parser = new DOMParser();
    const doc = parser.parseFromString(html, 'text/html');
    const headings = doc.querySelectorAll('h1, h2, h3, h4, h5, h6');
    
    headings.forEach(heading => {
      if (heading.id && heading.textContent) {
        toc.push({
          level: parseInt(heading.tagName.substring(1), 10),
          text: heading.textContent,
          id: heading.id
        });
      }
    });
    this.tableOfContents.set(toc);
  }
  
  scrollToHeading(id: string): void {
    // The note viewer component's content area is what scrolls
    const contentArea = (this.elementRef.nativeElement as HTMLElement).querySelector('.note-content-area');
    if(contentArea) {
      const element = contentArea.querySelector(`#${id}`);
      if (element) {
          element.scrollIntoView({ behavior: 'smooth', block: 'start' });
      }
    }
  }
}