"use client";

import { useState, useCallback, useEffect, useRef, useMemo } from "react";
import {
  EditorEventBus,
  type SubtitleData,
  type EditorEventType,
} from "./event-bus";
import {
  validateSubtitle,
  type ValidationIssue,
  type ValidationConfig,
  DEFAULT_VALIDATION,
} from "./validation";

export interface UseEditorOptions {
  initialSubtitles: SubtitleData[];
  jobId: string;
  resourceId?: string;
  editSessionId?: string;
  validationConfig?: ValidationConfig;
  fps?: number;
  autoSaveDelayMs?: number;
}

export type ValidationState = "none" | "validating" | "validated" | "reviewing";

export interface UseEditorReturn {
  subtitles: SubtitleData[];
  selectedIndex: number;
  setSelectedIndex: (index: number) => void;
  // Edit operations
  setText: (index: number, value: string) => void;
  setTimecodeIn: (index: number, value: string) => void;
  setTimecodeOut: (index: number, value: string) => void;
  setSpeaker: (index: number, value: string) => void;
  setComment: (index: number, value: string) => void;
  insertSubtitle: (atIndex: number) => void;
  deleteSubtitle: (index: number) => void;
  splitSubtitle: (index: number, splitPoint: number) => void;
  mergeWithNext: (index: number) => void;
  // Undo/redo
  undo: () => void;
  redo: () => void;
  canUndo: boolean;
  canRedo: boolean;
  // Validation
  validationIssues: Map<number, ValidationIssue[]>;
  totalErrors: number;
  totalWarnings: number;
  // Save state
  hasUnsavedChanges: boolean;
  isSaving: boolean;
  lastSavedAt: Date | null;
  saveNow: () => Promise<void>;
  // Rationale tracking (for diff capture)
  pendingRationales: Map<number, Map<string, string>>;
  setRationale: (index: number, field: string, rationale: string) => void;
  // Completion workflow
  editedIndices: Set<number>;
  editedIndicesWithoutRationale: Set<number>;
  canValidate: boolean;
  validationState: ValidationState;
  setValidationState: (state: ValidationState) => void;
  // Event bus (for NLI integration)
  eventBus: EditorEventBus;
}

export function useEditor(options: UseEditorOptions): UseEditorReturn {
  const {
    initialSubtitles,
    jobId,
    resourceId,
    editSessionId,
    validationConfig = DEFAULT_VALIDATION,
    fps = 23.976,
    autoSaveDelayMs = 5000,
  } = options;

  const eventBusRef = useRef<EditorEventBus>(
    new EditorEventBus(initialSubtitles)
  );
  const eventBus = eventBusRef.current;

  const [subtitles, setSubtitles] = useState<SubtitleData[]>(
    () => eventBus.getSubtitles()
  );
  const [selectedIndex, setSelectedIndex] = useState(0);
  const [canUndo, setCanUndo] = useState(false);
  const [canRedo, setCanRedo] = useState(false);
  const [hasUnsavedChanges, setHasUnsavedChanges] = useState(false);
  const [isSaving, setIsSaving] = useState(false);
  const [lastSavedAt, setLastSavedAt] = useState<Date | null>(null);
  const [pendingRationales, setPendingRationales] = useState<
    Map<number, Map<string, string>>
  >(new Map());
  const initialSubtitlesRef = useRef<SubtitleData[]>(structuredClone(initialSubtitles));
  const [validationState, setValidationState] = useState<ValidationState>("none");

  const saveTimerRef = useRef<ReturnType<typeof setTimeout>>();

  // Subscribe to event bus changes
  useEffect(() => {
    const unsubscribe = eventBus.subscribe(() => {
      setSubtitles([...eventBus.getSubtitles()]);
      setCanUndo(eventBus.canUndo());
      setCanRedo(eventBus.canRedo());
      setHasUnsavedChanges(eventBus.hasUnsavedChanges());

      // If ANY edit happens after validation, reset the cycle
      if (validationState !== "none") {
        setValidationState("none");
      }
    });
    return unsubscribe;
  }, [eventBus, validationState]);

  // Compute editedIndices by diffing current subtitles against initial state
  // If undo reverts a subtitle to its original, it drops out of this set
  const editedIndices = useMemo(() => {
    const edited = new Set<number>();
    const initial = initialSubtitlesRef.current;
    const current = subtitles;
    const len = Math.max(initial.length, current.length);
    for (let i = 0; i < len; i++) {
      const orig = initial[i];
      const curr = current[i];
      if (!orig || !curr) { edited.add(i); continue; }
      if (orig.text !== curr.text || orig.tcIn !== curr.tcIn || orig.tcOut !== curr.tcOut ||
          orig.speaker !== curr.speaker || orig.comment !== curr.comment) {
        edited.add(i);
      }
    }
    return edited;
  }, [subtitles]);

  // Validation
  const validationIssues = useMemo(() => {
    const issues = new Map<number, ValidationIssue[]>();
    for (let i = 0; i < subtitles.length; i++) {
      const subIssues = validateSubtitle(
        subtitles[i],
        i,
        subtitles,
        validationConfig,
        fps
      );
      if (subIssues.length > 0) {
        issues.set(i, subIssues);
      }
    }
    return issues;
  }, [subtitles, validationConfig, fps]);

  const totalErrors = useMemo(() => {
    let count = 0;
    validationIssues.forEach((issues) => {
      count += issues.filter((i) => i.severity === "error").length;
    });
    return count;
  }, [validationIssues]);

  const totalWarnings = useMemo(() => {
    let count = 0;
    validationIssues.forEach((issues) => {
      count += issues.filter((i) => i.severity === "warning").length;
    });
    return count;
  }, [validationIssues]);

  // Completion workflow: which edited subtitles are missing rationale
  const editedIndicesWithoutRationale = useMemo(() => {
    const missing = new Set<number>();
    for (const idx of editedIndices) {
      const ratMap = pendingRationales.get(idx);
      if (!ratMap || ratMap.size === 0) {
        missing.add(idx);
      } else {
        // Check if at least one rationale entry is non-empty
        const hasValue = [...ratMap.values()].some((v) => v.trim().length > 0);
        if (!hasValue) missing.add(idx);
      }
    }
    return missing;
  }, [editedIndices, pendingRationales]);

  // Validate is always available — missing rationales are surfaced as errors during validation, not as a blocker
  const canValidate = true;

  // Save function
  const saveNow = useCallback(async () => {
    if (!eventBus.hasUnsavedChanges()) return;
    setIsSaving(true);

    try {
      const changes = eventBus.flushChanges();

      // Build diffs from changes + rationales
      const fieldMap: Record<string, string> = {
        setText: "text",
        setTimecodeIn: "tc_in",
        setTimecodeOut: "tc_out",
        setSpeaker: "speaker",
        setComment: "comment",
        setPosition: "position",
        setStyle: "style",
      };

      const categoryMap: Record<string, string> = {
        setText: "translation_fix",
        setTimecodeIn: "timing_fix",
        setTimecodeOut: "timing_fix",
        setSpeaker: "other",
        setComment: "other",
        setPosition: "style_correction",
        setStyle: "style_correction",
        splitSubtitle: "split_merge",
        mergeSubtitles: "split_merge",
      };

      // Deduplicate: per (subtitleIndex + field), keep first oldValue and last newValue
      const diffMap = new Map<
        string,
        {
          subtitleIndex: number;
          field: string;
          oldValue: string | null;
          newValue: string | null;
          changeCategory: string;
        }
      >();

      for (const c of changes) {
        const field = fieldMap[c.type];
        if (!field) continue;

        const key = `${c.target}:${field}`;
        const existing = diffMap.get(key);
        const newValue =
          c.payload.value != null ? String(c.payload.value) : null;

        if (existing) {
          // Keep the original oldValue, update newValue to latest
          existing.newValue = newValue;
        } else {
          diffMap.set(key, {
            subtitleIndex: c.target,
            field,
            oldValue:
              c.previousValue != null ? String(c.previousValue) : null,
            newValue,
            changeCategory: categoryMap[c.type] || "other",
          });
        }
      }

      // Attach rationales and filter out no-ops
      const diffs = Array.from(diffMap.values())
        .filter((d) => d.oldValue !== d.newValue) // Skip no-ops
        .map((d) => ({
          ...d,
          rationale:
            pendingRationales.get(d.subtitleIndex)?.get(d.field) ||
            pendingRationales.get(d.subtitleIndex)?.values().next().value ||
            "Edit applied",
        }));

      // Build GTSDocument from current subtitles
      const document = {
        tracks: [
          {
            subtitles: subtitles.map((s) => ({
              tcIn: s.tcIn,
              tcOut: s.tcOut,
              text: s.text,
              speaker: s.speaker,
              comment: s.comment,
              position: s.position,
              style: s.style,
            })),
          },
        ],
      };

      await fetch(`/api/jobs/${jobId}/document`, {
        method: "PUT",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
          document,
          diffs: diffs.length > 0 ? diffs : undefined,
          resourceId,
          editSessionId,
        }),
      });

      setLastSavedAt(new Date());
      setHasUnsavedChanges(false);
      // Keep rationales visible — they persist until job is submitted/locked
      // The diffs already captured them server-side
    } catch (err) {
      console.error("Save failed:", err);
    } finally {
      setIsSaving(false);
    }
  }, [
    eventBus,
    subtitles,
    jobId,
    resourceId,
    editSessionId,
    pendingRationales,
  ]);

  // Auto-save
  useEffect(() => {
    if (hasUnsavedChanges) {
      clearTimeout(saveTimerRef.current);
      saveTimerRef.current = setTimeout(saveNow, autoSaveDelayMs);
    }
    return () => clearTimeout(saveTimerRef.current);
  }, [hasUnsavedChanges, saveNow, autoSaveDelayMs]);

  // Edit operations
  const setText = useCallback(
    (index: number, value: string) =>
      eventBus.dispatch({ type: "setText", target: index, payload: { value } }),
    [eventBus]
  );

  const setTimecodeIn = useCallback(
    (index: number, value: string) =>
      eventBus.dispatch({
        type: "setTimecodeIn",
        target: index,
        payload: { value },
      }),
    [eventBus]
  );

  const setTimecodeOut = useCallback(
    (index: number, value: string) =>
      eventBus.dispatch({
        type: "setTimecodeOut",
        target: index,
        payload: { value },
      }),
    [eventBus]
  );

  const setSpeaker = useCallback(
    (index: number, value: string) =>
      eventBus.dispatch({
        type: "setSpeaker",
        target: index,
        payload: { value },
      }),
    [eventBus]
  );

  const setComment = useCallback(
    (index: number, value: string) =>
      eventBus.dispatch({
        type: "setComment",
        target: index,
        payload: { value },
      }),
    [eventBus]
  );

  const insertSubtitle = useCallback(
    (atIndex: number) =>
      eventBus.dispatch({
        type: "insertSubtitle",
        target: atIndex,
        payload: {},
      }),
    [eventBus]
  );

  const deleteSubtitle = useCallback(
    (index: number) =>
      eventBus.dispatch({
        type: "deleteSubtitle",
        target: index,
        payload: {},
      }),
    [eventBus]
  );

  const splitSubtitle = useCallback(
    (index: number, splitPoint: number) =>
      eventBus.dispatch({
        type: "splitSubtitle",
        target: index,
        payload: { splitPoint },
      }),
    [eventBus]
  );

  const mergeWithNext = useCallback(
    (index: number) => {
      const next = eventBus.getSubtitle(index + 1);
      eventBus.dispatch({
        type: "mergeSubtitles",
        target: index,
        payload: { mergedSubtitle: next },
      });
    },
    [eventBus]
  );

  const undo = useCallback(() => eventBus.undo(), [eventBus]);
  const redo = useCallback(() => eventBus.redo(), [eventBus]);

  const setRationale = useCallback(
    (index: number, field: string, rationale: string) => {
      setPendingRationales((prev) => {
        const next = new Map(prev);
        const fieldMap = next.get(index) || new Map<string, string>();
        fieldMap.set(field, rationale);
        next.set(index, fieldMap);
        return next;
      });
    },
    []
  );

  return {
    subtitles,
    selectedIndex,
    setSelectedIndex,
    setText,
    setTimecodeIn,
    setTimecodeOut,
    setSpeaker,
    setComment,
    insertSubtitle,
    deleteSubtitle,
    splitSubtitle,
    mergeWithNext,
    undo,
    redo,
    canUndo,
    canRedo,
    validationIssues,
    totalErrors,
    totalWarnings,
    hasUnsavedChanges,
    isSaving,
    lastSavedAt,
    saveNow,
    pendingRationales,
    setRationale,
    editedIndices,
    editedIndicesWithoutRationale,
    canValidate,
    validationState,
    setValidationState,
    eventBus,
  };
}