import { useState, useCallback, useEffect, useRef } from "react";

const STORAGE_KEY = "forge-editor-state";

interface PersistedState {
  openTabs: string[];
  activeTab: string | null;
}

function loadPersistedState(): PersistedState {
  try {
    const raw = localStorage.getItem(STORAGE_KEY);
    if (raw) {
      const parsed = JSON.parse(raw);
      return {
        openTabs: Array.isArray(parsed.openTabs) ? parsed.openTabs : [],
        activeTab:
          typeof parsed.activeTab === "string" ? parsed.activeTab : null,
      };
    }
  } catch {
    // corrupted storage — start fresh
  }
  return { openTabs: [], activeTab: null };
}

function persistState(state: PersistedState) {
  try {
    localStorage.setItem(STORAGE_KEY, JSON.stringify(state));
  } catch {
    // quota exceeded — silently ignore
  }
}

export function useEditorState() {
  const [openTabs, setOpenTabs] = useState<string[]>(
    () => loadPersistedState().openTabs,
  );
  const [activeTab, setActiveTab] = useState<string | null>(
    () => loadPersistedState().activeTab,
  );
  const [dirtyFiles, setDirtyFiles] = useState<Set<string>>(new Set());
  const fileContents = useRef<Map<string, string>>(new Map());

  useEffect(() => {
    persistState({ openTabs, activeTab });
  }, [openTabs, activeTab]);

  const openFile = useCallback(
    (path: string, content?: string) => {
      if (content !== undefined) {
        fileContents.current.set(path, content);
      }
      setOpenTabs((prev) => {
        if (prev.includes(path)) return prev;
        return [...prev, path];
      });
      setActiveTab(path);
    },
    [],
  );

  const closeFile = useCallback(
    (path: string) => {
      setOpenTabs((prev) => {
        const next = prev.filter((p) => p !== path);
        setActiveTab((current) => {
          if (current !== path) return current;
          const idx = prev.indexOf(path);
          return next[Math.min(idx, next.length - 1)] ?? null;
        });
        return next;
      });
      setDirtyFiles((prev) => {
        const next = new Set(prev);
        next.delete(path);
        return next;
      });
      fileContents.current.delete(path);
    },
    [],
  );

  const selectTab = useCallback((path: string) => {
    setActiveTab(path);
  }, []);

  const markDirty = useCallback((path: string) => {
    setDirtyFiles((prev) => {
      if (prev.has(path)) return prev;
      return new Set(prev).add(path);
    });
  }, []);

  const markClean = useCallback((path: string) => {
    setDirtyFiles((prev) => {
      if (!prev.has(path)) return prev;
      const next = new Set(prev);
      next.delete(path);
      return next;
    });
  }, []);

  const updateContent = useCallback(
    (path: string, content: string) => {
      fileContents.current.set(path, content);
      markDirty(path);
    },
    [markDirty],
  );

  const getContent = useCallback((path: string): string | undefined => {
    return fileContents.current.get(path);
  }, []);

  return {
    openTabs,
    activeTab,
    dirtyFiles,
    openFile,
    closeFile,
    selectTab,
    markDirty,
    markClean,
    updateContent,
    getContent,
  };
}