import { Editor } from '../../editor/Editor.js';

// ── Layout helpers ────────────────────────────────────────────────────────────

let tcCounter = 0;
function nextTcId(): string { return `tc-${++tcCounter}`; }

function makeResizeHandle(direction: 'v' | 'h'): HTMLElement {
  const h = document.createElement('div');
  h.className = direction === 'v' ? 'es-v-handle' : 'es-h-handle';
  h.addEventListener('pointerdown', (e: PointerEvent) => {
    e.preventDefault();
    h.setPointerCapture(e.pointerId);
    const prev = h.previousElementSibling as HTMLElement | null;
    const next = h.nextElementSibling as HTMLElement | null;
    if (!prev || !next) return;
    const startPos = direction === 'v' ? e.clientX : e.clientY;
    const startPrev = direction === 'v' ? prev.offsetWidth : prev.offsetHeight;
    const startNext = direction === 'v' ? next.offsetWidth : next.offsetHeight;
    const total = startPrev + startNext;

    const onMove = (ev: PointerEvent) => {
      const delta = (direction === 'v' ? ev.clientX : ev.clientY) - startPos;
      const newPrev = Math.max(60, Math.min(total - 60, startPrev + delta));
      prev.style.flexBasis = `${newPrev}px`;
      next.style.flexBasis = `${total - newPrev}px`;
      prev.style.flex = `0 0 ${newPrev}px`;
      next.style.flex = `0 0 ${total - newPrev}px`;
    };
    h.addEventListener('pointermove', onMove);
    h.addEventListener('pointerup', () => h.removeEventListener('pointermove', onMove), { once: true });
  });
  return h;
}

function makeSection(): HTMLElement {
  const sec = document.createElement('div');
  sec.className = 'es-section';
  const tc = document.createElement('tab-container') as HTMLElement;
  tc.id = nextTcId();
  sec.appendChild(tc);
  return sec;
}

function makePanelInner(): HTMLElement {
  const inner = document.createElement('div');
  inner.className = 'es-sections';
  const sec = makeSection();
  inner.appendChild(sec);
  return inner;
}

// ── EditorShell ───────────────────────────────────────────────────────────────

class EditorShell extends HTMLElement {
  private activePortraitPanel: string = 'center';
  private _deviceId: string = '';
  private _saveTimer: ReturnType<typeof setTimeout> | null = null;

  async connectedCallback(): Promise<void> {
    const authRes = await fetch( '/api/auth/me' );
    if ( !authRes.ok ) { location.href = '/'; return; }

    const params = new URLSearchParams(location.search);
    const projectId = params.get('project') ?? '';
    const projectName = params.get('name') ?? 'Project';
    Editor.get().projectId = projectId;
    Editor.get().projectName = projectName;

    this.innerHTML = `
      <div class="es-header">
        <a class="es-back" href="/">←</a>
        <span class="es-title">${projectName}</span>
        <div class="es-portrait-btns">
          <button class="es-pb-btn" data-panel="left">⊟</button>
          <button class="es-pb-btn active" data-panel="center">⊡</button>
          <button class="es-pb-btn" data-panel="right">⊞</button>
        </div>
      </div>
      <div class="es-workspace">
        <div class="es-panel" data-panel="left">${makePanelInner().outerHTML}</div>
        <div class="es-v-handle"></div>
        <div class="es-panel" data-panel="center">${makePanelInner().outerHTML}</div>
        <div class="es-v-handle"></div>
        <div class="es-panel" data-panel="right">${makePanelInner().outerHTML}</div>
      </div>
    `;

    this.setupMainHandles();
    this.setupPortrait();
    this.setupSplitListener();
    this.setupResizeHandler();

    await Promise.all( [
      customElements.whenDefined( 'tab-container' ),
      customElements.whenDefined( 'file-tree-panel' ),
      customElements.whenDefined( 'page-editor-panel' ),
      customElements.whenDefined( 'code-panel' ),
      this._loadLayout(),
    ] );

    this.initDefaultLayout();
  }

  private initDefaultLayout(): void {
    const leftTc = this.querySelector('[data-panel="left"] tab-container') as any;
    const centerTc = this.querySelector('[data-panel="center"] tab-container') as any;

    leftTc?.addTab({ id: 'file-tree', label: 'Files', panelType: 'file-tree' }, () => {
      return document.createElement('file-tree-panel');
    });

    centerTc?.addTab({ id: 'page-editor', label: 'Page', panelType: 'page-editor' }, () => {
      return document.createElement('page-editor-panel');
    });
  }

  private setupMainHandles(): void {
    const workspace = this.querySelector('.es-workspace')!;
    workspace.querySelectorAll(':scope > .es-v-handle').forEach(h => {
      const handle = h as HTMLElement;
      handle.addEventListener('pointerdown', (e: PointerEvent) => {
        e.preventDefault();
        handle.setPointerCapture(e.pointerId);
        const prev = handle.previousElementSibling as HTMLElement;
        const next = handle.nextElementSibling as HTMLElement;
        const start = e.clientX;
        const startPrev = prev.offsetWidth;
        const startNext = next.offsetWidth;
        const total = startPrev + startNext;

        const onMove = (ev: PointerEvent) => {
          const delta = ev.clientX - start;
          const np = Math.max(80, Math.min(total - 80, startPrev + delta));
          prev.style.flex = `0 0 ${np}px`;
          next.style.flex = `0 0 ${total - np}px`;
        };
        handle.addEventListener('pointermove', onMove);
        handle.addEventListener('pointerup', () => {
          handle.removeEventListener('pointermove', onMove);
          this._scheduleLayoutSave();
        }, { once: true });
      });
    });

    this.querySelectorAll('.es-sections').forEach(sections => {
      this.observeNewHandles(sections as HTMLElement);
    });

  }

  private setupSplitListener(): void {
    this.addEventListener('tab-container:split', (e: Event) => {
      const { containerId } = (e as CustomEvent).detail as { containerId: string };
      const tc = document.getElementById(containerId);
      if (!tc) return;
      const section = tc.closest('.es-section') as HTMLElement | null;
      const sections = tc.closest('.es-sections') as HTMLElement | null;
      if (!section || !sections) return;
      const newSec = makeSection();
      const handle = makeResizeHandle('v');
      sections.insertBefore(handle, section.nextSibling);
      sections.insertBefore(newSec, handle.nextSibling);
    });

    this.addEventListener('tab-container:add-panel', (e: Event) => {
      const { containerId, panelType, tag, label } = (e as CustomEvent).detail as { containerId: string; panelType: string; tag: string; label: string };
      const tc = document.getElementById(containerId) as any;
      if (!tc) return;
      const id = panelType + '-' + Math.random().toString(36).slice(2);
      tc.addTab({ id, label: label ?? panelType, panelType }, () => document.createElement(tag));
    });
  }

  private _getDeviceId(): string
  {
    if ( this._deviceId ) return this._deviceId;
    let id = localStorage.getItem( 'roject:deviceId' );
    if ( !id )
    {
      id = Math.random().toString( 36 ).slice( 2 ) + Math.random().toString( 36 ).slice( 2 );
      localStorage.setItem( 'roject:deviceId', id );
    }
    this._deviceId = id;
    return id;
  }

  private async _loadLayout(): Promise<void>
  {
    try
    {
      const res = await fetch( `/api/layout?deviceId=${this._getDeviceId()}` );
      if ( !res.ok ) return;
      const layout = await res.json();
      if ( !layout ) return;

      if ( layout.panels )
      {
        const workspace = this.querySelector( '.es-workspace' ) as HTMLElement;
        for ( const [ panel, flex ] of Object.entries( layout.panels ) )
        {
          if ( flex )
          {
            const el = workspace.querySelector( `[data-panel="${panel}"]` ) as HTMLElement;
            if ( el ) el.style.flex = flex as string;
          }
        }
      }

      if ( layout.activePortraitPanel )
      {
        this.activePortraitPanel = layout.activePortraitPanel;
      }
    }
    catch {}
  }

  private _scheduleLayoutSave(): void
  {
    if ( this._saveTimer ) clearTimeout( this._saveTimer );
    this._saveTimer = setTimeout( () => this._saveLayout(), 800 );
  }

  private async _saveLayout(): Promise<void>
  {
    const workspace = this.querySelector( '.es-workspace' ) as HTMLElement;
    const panels: Record<string, string | null> = {};
    for ( const p of [ 'left', 'center', 'right' ] )
    {
      const el = workspace.querySelector( `[data-panel="${p}"]` ) as HTMLElement;
      panels[ p ] = el?.style.flex || null;
    }
    const layout = { panels, activePortraitPanel: this.activePortraitPanel };
    try
    {
      await fetch( `/api/layout?deviceId=${this._getDeviceId()}`, {
        method: 'PUT',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify( layout ),
      } );
    }
    catch {}
  }

  private setupResizeHandler(): void
  {
    const workspace = this.querySelector( '.es-workspace' ) as HTMLElement;
    const obs = new ResizeObserver( () =>
    {
      this._redistributeFlex( workspace, '.es-panel' );
      workspace.querySelectorAll( '.es-sections' ).forEach( container =>
      {
        this._redistributeFlex( container as HTMLElement, '.es-section' );
      } );
    } );
    obs.observe( workspace );
  }

  private _redistributeFlex( container: HTMLElement, childSelector: string ): void
  {
    const children = Array.from( container.querySelectorAll( `:scope > ${childSelector}` ) ) as HTMLElement[];
    if ( children.length < 2 ) return;
    if ( ! children.some( c => c.style.flex ) ) return;

    const totalPanel = children.reduce( ( sum, c ) => sum + c.offsetWidth, 0 );
    if ( totalPanel === 0 ) return;

    const handles = Array.from( container.children ).filter(
      c => ! ( c as HTMLElement ).matches( childSelector )
    ) as HTMLElement[];
    const handleTotal = handles.reduce( ( sum, h ) => sum + ( h as HTMLElement ).offsetWidth, 0 );
    const available = container.clientWidth - handleTotal;

    children.forEach( c =>
    {
      const ratio = c.offsetWidth / totalPanel;
      c.style.flex = `0 0 ${Math.round( ratio * available )}px`;
    } );
  }

  private observeNewHandles(sections: HTMLElement): void {
    const observer = new MutationObserver(() => {
      sections.querySelectorAll('.es-h-handle:not([data-bound])').forEach(h => {
        (h as HTMLElement).dataset.bound = '1';
      });
    });
    observer.observe(sections, { childList: true });
  }

  private setupPortrait(): void {
    const btns = this.querySelector( '.es-portrait-btns' ) as HTMLElement;
    const mq = window.matchMedia( '(orientation: portrait)' );

    const apply = ( portrait: boolean ) => {
      this.classList.toggle( 'portrait', portrait );
      if ( portrait ) this.showPortraitPanel( this.activePortraitPanel );
    };

    btns.querySelectorAll( '.es-pb-btn' ).forEach( btn => {
      btn.addEventListener( 'click', () => {
        const panel = ( btn as HTMLElement ).dataset.panel!;
        this.activePortraitPanel = panel;
        btns.querySelectorAll( '.es-pb-btn' ).forEach( b => b.classList.remove( 'active' ) );
        btn.classList.add( 'active' );
        this.showPortraitPanel( panel );
        this._scheduleLayoutSave();
      } );
    } );

    mq.addEventListener( 'change', e => apply( e.matches ) );
    apply( mq.matches );
  }

  private showPortraitPanel(panelId: string): void {
    this.querySelectorAll('.es-panel').forEach(p => {
      (p as HTMLElement).style.display = (p as HTMLElement).dataset.panel === panelId ? '' : 'none';
    });
    this.querySelectorAll('.es-v-handle').forEach(h => { (h as HTMLElement).style.display = 'none'; });
  }
}

customElements.define('editor-shell', EditorShell);