import { ArrowLeft, ArrowRight, Maximize2, Minimize2 } from "lucide-react";
import { useCallback, useEffect, useRef, useState, type PointerEvent as ReactPointerEvent, type ReactNode } from "react";
import { ErrorRibbon } from "../components/ui";
import { navigate } from "../router";
import {
  enterElementFullscreen,
  exitElementFullscreen,
  isElementFullscreen,
  isReaderHeaderActive,
  readerNavigationAction,
  shouldHandleReaderNavigationKey,
  supportsElementFullscreen
} from "./readerFullscreen";
import { readerMovedBeyondTap, readerPinchZoom, readerPointDistance, type ReaderPoint } from "./readerGestures";
import { readerZoomLabel, READER_ZOOM_DEFAULT, READER_ZOOM_MAX, READER_ZOOM_MIN } from "./readerLayout";
import type { ReaderMode } from "./readerScroll";
import type { ReadingConnectionMode } from "../api/types";

export type ReaderControls = {
  canPrevious: boolean;
  canNext: boolean;
  positionLabel: string;
  onPrevious: () => void;
  onNext: () => void;
};

export type ReaderZoomControls = {
  zoom: number;
  onZoomChange: (zoom: number, anchor?: ReaderZoomAnchor) => void;
  onZoomOut: () => void;
  onZoomIn: () => void;
  onZoomReset: () => void;
};

export type ReaderModeControls = {
  mode: ReaderMode;
  onModeChange: (mode: ReaderMode) => void;
};

export type ReaderConnectionControls = {
  mode: ReadingConnectionMode;
  onModeChange: (mode: ReadingConnectionMode) => void;
};

type ReaderShellProps = {
  title: string;
  backHref: string;
  error?: string;
  onRetry?: () => void;
  controls: ReaderControls;
  zoomControls?: ReaderZoomControls;
  modeControls?: ReaderModeControls;
  connectionControls?: ReaderConnectionControls;
  activity?: string;
  children: ReactNode;
};

export type ReaderZoomAnchor = {
  page: number;
  clientX: number;
  clientY: number;
  offsetX: number;
  offsetY: number;
  ratioX: number;
  ratioY: number;
};

type ReaderPinchGesture = {
  distance: number;
  zoom: number;
  anchor: ReaderZoomAnchor | null;
};

function readerTouchPoint(touch: Touch): ReaderPoint {
  return { x: touch.clientX, y: touch.clientY };
}

function readerTouchMidpoint(first: Touch, second: Touch): ReaderPoint {
  return {
    x: (first.clientX + second.clientX) / 2,
    y: (first.clientY + second.clientY) / 2
  };
}

function readerZoomAnchorAt(point: ReaderPoint): ReaderZoomAnchor | null {
  const pageElement = document.elementFromPoint(point.x, point.y)?.closest("[data-reader-page]");
  if (!(pageElement instanceof HTMLElement)) return null;
  const page = Number(pageElement.dataset.readerPage);
  const rect = pageElement.getBoundingClientRect();
  if (!Number.isFinite(page) || rect.width <= 0 || rect.height <= 0) return null;
  return {
    page,
    clientX: point.x,
    clientY: point.y,
    offsetX: point.x - rect.left,
    offsetY: point.y - rect.top,
    ratioX: Math.max(0, Math.min(1, (point.x - rect.left) / rect.width)),
    ratioY: Math.max(0, Math.min(1, (point.y - rect.top) / rect.height))
  };
}

function restoreReaderZoomAnchor(stage: HTMLElement, anchor: ReaderZoomAnchor) {
  const target = stage.querySelector<HTMLElement>(`[data-reader-page="${anchor.page}"]`);
  if (!target) return;
  const rect = target.getBoundingClientRect();
  stage.scrollLeft += rect.left + anchor.offsetX - anchor.clientX;
  stage.scrollTop += rect.top + anchor.offsetY - anchor.clientY;
}

function scheduleReaderZoomAnchorRestore(stage: HTMLElement, anchor: ReaderZoomAnchor) {
  requestAnimationFrame(() => {
    requestAnimationFrame(() => restoreReaderZoomAnchor(stage, anchor));
  });
}

export function ReaderShell({ title, backHref, error, onRetry, controls, zoomControls, modeControls, connectionControls, activity, children }: ReaderShellProps) {
  const readerRef = useRef<HTMLDivElement>(null);
  const headerRef = useRef<HTMLElement>(null);
  const stageRef = useRef<HTMLElement>(null);
  const headerHideTimerRef = useRef<number | undefined>(undefined);
  const tapStartRef = useRef<ReaderPoint | null>(null);
  const activeTouchPointsRef = useRef(new Map<number, ReaderPoint>());
  const pinchRef = useRef<ReaderPinchGesture | null>(null);
  const [nativeFullscreen, setNativeFullscreen] = useState(false);
  const [fallbackFullscreen, setFallbackFullscreen] = useState(false);
  const [headerVisible, setHeaderVisible] = useState(true);
  const fullscreenActive = nativeFullscreen || fallbackFullscreen;
  const readerMode = modeControls?.mode ?? "horizontal";

  const isMobileReaderViewport = useCallback(() => window.matchMedia("(max-width: 900px) and (pointer: coarse)").matches, []);

  const shouldUseTapOnlyHeaderReveal = useCallback(() => readerMode === "vertical" && isMobileReaderViewport(), [isMobileReaderViewport, readerMode]);

  const clearHeaderHideTimer = useCallback(() => {
    if (headerHideTimerRef.current === undefined) return;
    window.clearTimeout(headerHideTimerRef.current);
    headerHideTimerRef.current = undefined;
  }, []);

  const scheduleHeaderHide = useCallback(() => {
    clearHeaderHideTimer();
    if (!fullscreenActive) {
      setHeaderVisible(true);
      return;
    }
    headerHideTimerRef.current = window.setTimeout(() => {
      if (isReaderHeaderActive(headerRef.current, document)) {
        scheduleHeaderHide();
        return;
      }
      setHeaderVisible(false);
    }, 2000);
  }, [clearHeaderHideTimer, fullscreenActive]);

  const revealHeader = useCallback(() => {
    if (!fullscreenActive) return;
    setHeaderVisible(true);
    scheduleHeaderHide();
  }, [fullscreenActive, scheduleHeaderHide]);

  const revealHeaderForPassiveGesture = useCallback(() => {
    if (shouldUseTapOnlyHeaderReveal()) return;
    revealHeader();
  }, [revealHeader, shouldUseTapOnlyHeaderReveal]);

  const toggleFullscreen = useCallback(async () => {
    const readerElement = readerRef.current;
    if (!readerElement) return;

    if (isElementFullscreen(readerElement, document)) {
      await exitElementFullscreen(document);
      return;
    }

    if (fallbackFullscreen) {
      setFallbackFullscreen(false);
      return;
    }

    if (supportsElementFullscreen(readerElement)) {
      try {
        await enterElementFullscreen(readerElement);
        return;
      } catch {
        setFallbackFullscreen(true);
        return;
      }
    }

    setFallbackFullscreen(true);
  }, [fallbackFullscreen]);

  useEffect(() => {
    const syncFullscreen = () => {
      const readerElement = readerRef.current;
      setNativeFullscreen(isElementFullscreen(readerElement, document));
    };
    syncFullscreen();
    document.addEventListener("fullscreenchange", syncFullscreen);
    return () => document.removeEventListener("fullscreenchange", syncFullscreen);
  }, []);

  useEffect(() => {
    if (fullscreenActive) {
      setHeaderVisible(true);
      scheduleHeaderHide();
      return;
    }
    clearHeaderHideTimer();
    setHeaderVisible(true);
  }, [clearHeaderHideTimer, fullscreenActive, scheduleHeaderHide]);

  useEffect(() => clearHeaderHideTimer, [clearHeaderHideTimer]);

  useEffect(() => {
    const handleKeyDown = (event: KeyboardEvent) => {
      if (event.key === "Escape" && fallbackFullscreen) {
        setFallbackFullscreen(false);
        return;
      }
      const mode = modeControls?.mode ?? "horizontal";
      if (!shouldHandleReaderNavigationKey(event, readerRef.current, mode)) return;
      revealHeader();
      const action = readerNavigationAction(event, mode);
      if (mode === "vertical") {
        event.preventDefault();
        stageRef.current?.scrollBy({ top: (action === "next" ? 1 : -1) * Math.max(120, stageRef.current.clientHeight * 0.82), behavior: "smooth" });
        return;
      }
      if (action === "previous" && controls.canPrevious) {
        event.preventDefault();
        controls.onPrevious();
      }
      if (action === "next" && controls.canNext) {
        event.preventDefault();
        controls.onNext();
      }
    };
    window.addEventListener("keydown", handleKeyDown);
    return () => window.removeEventListener("keydown", handleKeyDown);
  }, [controls, fallbackFullscreen, modeControls?.mode, revealHeader]);

  useEffect(() => {
    const stage = stageRef.current;
    if (!stage || !zoomControls) return;

    const startPinch = (event: TouchEvent) => {
      if (!isMobileReaderViewport() || event.touches.length !== 2) {
        pinchRef.current = null;
        stage.removeAttribute("data-reader-pinch-active");
        return;
      }
      event.preventDefault();
      const midpoint = readerTouchMidpoint(event.touches[0], event.touches[1]);
      const distance = readerPointDistance(readerTouchPoint(event.touches[0]), readerTouchPoint(event.touches[1]));
      stage.dataset.readerPinchActive = "true";
      tapStartRef.current = null;
      pinchRef.current = { distance, zoom: zoomControls.zoom, anchor: readerZoomAnchorAt(midpoint) };
    };
    const movePinch = (event: TouchEvent) => {
      if (!pinchRef.current || event.touches.length !== 2) return;
      event.preventDefault();
      const midpoint = readerTouchMidpoint(event.touches[0], event.touches[1]);
      const distance = readerPointDistance(readerTouchPoint(event.touches[0]), readerTouchPoint(event.touches[1]));
      const anchor = pinchRef.current.anchor ? { ...pinchRef.current.anchor, clientX: midpoint.x, clientY: midpoint.y } : null;
      zoomControls.onZoomChange(readerPinchZoom(pinchRef.current.zoom, pinchRef.current.distance, distance), anchor ?? undefined);
      if (anchor) scheduleReaderZoomAnchorRestore(stage, anchor);
    };
    const endPinch = (event: TouchEvent) => {
      if (event.touches.length >= 2) return;
      pinchRef.current = null;
      stage.removeAttribute("data-reader-pinch-active");
    };

    stage.addEventListener("touchstart", startPinch, { passive: false });
    stage.addEventListener("touchmove", movePinch, { passive: false });
    stage.addEventListener("touchend", endPinch);
    stage.addEventListener("touchcancel", endPinch);
    return () => {
      stage.removeEventListener("touchstart", startPinch);
      stage.removeEventListener("touchmove", movePinch);
      stage.removeEventListener("touchend", endPinch);
      stage.removeEventListener("touchcancel", endPinch);
    };
  }, [isMobileReaderViewport, zoomControls]);

  const handleReaderPointerDown = useCallback(
    (event: ReactPointerEvent<HTMLDivElement>) => {
      if (!shouldUseTapOnlyHeaderReveal()) {
        revealHeader();
        return;
      }
      if (event.pointerType !== "touch" || !event.isPrimary || activeTouchPointsRef.current.size > 0) {
        tapStartRef.current = null;
        return;
      }
      activeTouchPointsRef.current.set(event.pointerId, { x: event.clientX, y: event.clientY });
      tapStartRef.current = { x: event.clientX, y: event.clientY };
    },
    [revealHeader, shouldUseTapOnlyHeaderReveal]
  );

  const handleReaderPointerMove = useCallback(
    (event: ReactPointerEvent<HTMLDivElement>) => {
      if (!shouldUseTapOnlyHeaderReveal()) return;
      const current = { x: event.clientX, y: event.clientY };
      if (activeTouchPointsRef.current.has(event.pointerId)) activeTouchPointsRef.current.set(event.pointerId, current);
      const tapStart = tapStartRef.current;
      if (tapStart && readerMovedBeyondTap(tapStart, current)) tapStartRef.current = null;
    },
    [shouldUseTapOnlyHeaderReveal]
  );

  const handleReaderPointerUp = useCallback(
    (event: ReactPointerEvent<HTMLDivElement>) => {
      if (!shouldUseTapOnlyHeaderReveal()) return;
      activeTouchPointsRef.current.delete(event.pointerId);
      const tapStart = tapStartRef.current;
      tapStartRef.current = null;
      if (event.pointerType === "touch" && event.isPrimary && tapStart && !readerMovedBeyondTap(tapStart, { x: event.clientX, y: event.clientY })) {
        revealHeader();
      }
    },
    [revealHeader, shouldUseTapOnlyHeaderReveal]
  );

  const handleReaderPointerCancel = useCallback((event: ReactPointerEvent<HTMLDivElement>) => {
    activeTouchPointsRef.current.delete(event.pointerId);
    tapStartRef.current = null;
  }, []);

  return (
    <div
      ref={readerRef}
      className={`reader-page reader-mode-${readerMode}${fallbackFullscreen ? " reader-fullscreen-fallback" : ""}${fullscreenActive ? " reader-fullscreen-active" : ""}${
        fullscreenActive && !headerVisible ? " reader-header-hidden" : ""
      }`}
      onMouseMove={revealHeaderForPassiveGesture}
      onPointerDown={handleReaderPointerDown}
      onPointerMove={handleReaderPointerMove}
      onPointerUp={handleReaderPointerUp}
      onPointerCancel={handleReaderPointerCancel}
      onScrollCapture={revealHeaderForPassiveGesture}
      onWheel={revealHeaderForPassiveGesture}
    >
      <header
        ref={headerRef}
        className="reader-topbar"
        onBlur={scheduleHeaderHide}
        onFocus={() => {
          clearHeaderHideTimer();
          setHeaderVisible(true);
        }}
        onMouseEnter={() => {
          clearHeaderHideTimer();
          setHeaderVisible(true);
        }}
        onMouseLeave={scheduleHeaderHide}
        onPointerDown={() => {
          clearHeaderHideTimer();
          setHeaderVisible(true);
        }}
      >
        <button className="ghost-button reader-back-button" onClick={() => navigate(backHref)} aria-label="Retour">
          <ArrowLeft size={17} />
          <span>Retour</span>
        </button>
        <strong className="reader-title">{title}</strong>
        <span className="reader-position">{controls.positionLabel}</span>
        {modeControls && (
          <label className="reader-mode-control">
            <span>Mode de lecture</span>
            <select value={modeControls.mode} onChange={(event) => modeControls.onModeChange(event.currentTarget.value as ReaderMode)}>
              <option value="horizontal">Page par page</option>
              <option value="vertical">Défilement vertical</option>
            </select>
          </label>
        )}
        {connectionControls && (
          <label className="reader-mode-control reader-connection-control">
            <span>Mode connexion lente</span>
            <select value={connectionControls.mode} onChange={(event) => connectionControls.onModeChange(event.currentTarget.value as ReadingConnectionMode)}>
              <option value="auto">Automatique</option>
              <option value="speed">Toujours privilégier la vitesse</option>
              <option value="quality">Toujours privilégier la qualité</option>
            </select>
          </label>
        )}
        <button className="ghost-button reader-nav-button reader-previous-button" onClick={controls.onPrevious} disabled={!controls.canPrevious} aria-label="Page precedente">
          <ArrowLeft size={16} />
          <span>Precedent</span>
        </button>
        <button className="ghost-button reader-nav-button reader-next-button" onClick={controls.onNext} disabled={!controls.canNext} aria-label="Page suivante">
          <span>Suivant</span>
          <ArrowRight size={16} />
        </button>
        {zoomControls && (
          <div className="reader-zoom-controls" aria-label="Zoom du lecteur">
            <button className="ghost-button reader-zoom-button" onClick={zoomControls.onZoomOut} disabled={zoomControls.zoom <= READER_ZOOM_MIN} aria-label="Reduire le zoom">
              -
            </button>
            <span className="reader-zoom-label">{readerZoomLabel(zoomControls.zoom)}</span>
            <button className="ghost-button reader-zoom-button" onClick={zoomControls.onZoomIn} disabled={zoomControls.zoom >= READER_ZOOM_MAX} aria-label="Augmenter le zoom">
              +
            </button>
            <button className="ghost-button reader-zoom-reset" onClick={zoomControls.onZoomReset} disabled={zoomControls.zoom === READER_ZOOM_DEFAULT}>
              Réinitialiser
            </button>
          </div>
        )}
        <button className="ghost-button reader-fullscreen-toggle" onClick={() => void toggleFullscreen()} aria-pressed={fullscreenActive} aria-label={fullscreenActive ? "Quitter le plein écran" : "Plein écran"}>
          {fullscreenActive ? <Minimize2 size={16} /> : <Maximize2 size={16} />}
          <span>{fullscreenActive ? "Quitter le plein écran" : "Plein écran"}</span>
        </button>
      </header>
      {error && (
        <div className="reader-status">
          <ErrorRibbon message={error} />
          {onRetry && (
            <button className="ghost-button" onClick={onRetry}>
              Reessayer
            </button>
          )}
        </div>
      )}
      {!error && activity && (
        <div className="reader-status reader-activity" role="status" aria-live="polite">
          <span>{activity}</span>
        </div>
      )}
      <main className="reader-stage" ref={stageRef}>
        <div className="reader-content">{children}</div>
      </main>
    </div>
  );
}