import type {
  FlowBoardDraft,
  FlowBoardSheetSnapshotData,
  FlowBoardSnapshotData,
} from "@/lib/db/schema";

export function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}

function normalizeRecord(value: unknown): Record<string, unknown> | null {
  return isRecord(value) ? value : null;
}

const DEFAULT_FLOW_BOARD_CANVAS = {
  backgroundColor: "#f7f8fb",
  gridColor: "#d8dde8",
  gridEnabled: false,
  gridSize: 24,
};

function normalizeCanvasColor(value: unknown, fallback: string) {
  return typeof value === "string" && /^#[0-9a-f]{6}$/i.test(value)
    ? value.toLowerCase()
    : fallback;
}

function normalizeFlowBoardCanvas(value: unknown): Record<string, unknown> {
  const canvas = isRecord(value) ? value : {};
  const requestedGridSize =
    typeof canvas.gridSize === "number" && Number.isFinite(canvas.gridSize)
      ? Math.round(canvas.gridSize)
      : DEFAULT_FLOW_BOARD_CANVAS.gridSize;

  return {
    backgroundColor: normalizeCanvasColor(
      canvas.backgroundColor,
      DEFAULT_FLOW_BOARD_CANVAS.backgroundColor
    ),
    gridColor: normalizeCanvasColor(
      canvas.gridColor,
      DEFAULT_FLOW_BOARD_CANVAS.gridColor
    ),
    gridEnabled:
      typeof canvas.gridEnabled === "boolean"
        ? canvas.gridEnabled
        : DEFAULT_FLOW_BOARD_CANVAS.gridEnabled,
    gridSize: Math.min(64, Math.max(8, requestedGridSize)),
  };
}

function normalizeSheetId(value: unknown, index: number) {
  const id = typeof value === "string" ? value.trim().slice(0, 128) : "";
  return id || `sheet-${index + 1}`;
}

function normalizeSheetTitle(value: unknown, index: number) {
  const title = typeof value === "string" ? value.trim().slice(0, 128) : "";
  return title || `画布 ${index + 1}`;
}

function normalizeFlowBoardSheet(
  value: unknown,
  index: number
): FlowBoardSheetSnapshotData | null {
  if (!isRecord(value)) {
    return null;
  }

  return {
    id: normalizeSheetId(value.id, index),
    title: normalizeSheetTitle(value.title, index),
    children: Array.isArray(value.children)
      ? value.children.filter(isRecord)
      : [],
    viewport: normalizeRecord(value.viewport),
    theme: normalizeRecord(value.theme),
    canvas: normalizeFlowBoardCanvas(value.canvas),
  };
}

export function normalizeFlowBoardTitle(value: unknown) {
  const title = String(value || "").trim();
  return title.slice(0, 256) || "未命名流程白板";
}

export function normalizeFlowBoardSnapshot(
  value: unknown
): FlowBoardSnapshotData {
  const raw = isRecord(value) ? value : {};
  const legacyChildren = Array.isArray(raw.children)
    ? raw.children.filter(isRecord)
    : [];
  const normalizedSheets = Array.isArray(raw.sheets)
    ? raw.sheets
        .map(normalizeFlowBoardSheet)
        .filter(
          (sheet): sheet is FlowBoardSheetSnapshotData => Boolean(sheet)
        )
    : [];
  const sheets =
    normalizedSheets.length > 0
      ? normalizedSheets
      : [
          {
            id: "sheet-1",
            title: "画布 1",
            children: legacyChildren,
            viewport: normalizeRecord(raw.viewport),
            theme: normalizeRecord(raw.theme),
            canvas: normalizeFlowBoardCanvas(raw.canvas),
          },
        ];
  const requestedActiveSheetId =
    typeof raw.activeSheetId === "string" ? raw.activeSheetId.trim() : "";
  const activeSheet =
    sheets.find((sheet) => sheet.id === requestedActiveSheetId) || sheets[0];
  const activeChildren = Array.isArray(raw.children)
    ? legacyChildren
    : activeSheet.children;
  const activeViewport = isRecord(raw.viewport)
    ? raw.viewport
    : activeSheet.viewport;
  const activeTheme = isRecord(raw.theme) ? raw.theme : activeSheet.theme;
  const activeCanvas = isRecord(raw.canvas)
    ? normalizeFlowBoardCanvas(raw.canvas)
    : normalizeFlowBoardCanvas(activeSheet.canvas);
  const nextSheets = sheets.map((sheet) =>
    sheet.id === activeSheet.id
      ? {
          ...sheet,
          children: activeChildren,
          viewport: activeViewport,
          theme: activeTheme,
          canvas: activeCanvas,
        }
      : sheet
  );
  const updatedAt =
    typeof raw.updatedAt === "string" && raw.updatedAt.trim()
      ? raw.updatedAt
      : new Date().toISOString();

  return {
    version: 2,
    activeSheetId: activeSheet.id,
    sheets: nextSheets,
    children: activeChildren,
    viewport: activeViewport,
    theme: activeTheme,
    canvas: activeCanvas,
    updatedAt,
  };
}

export function mapFlowBoardDraft(draft: FlowBoardDraft) {
  return {
    id: draft.id,
    title: draft.title || "未命名流程白板",
    snapshot: draft.snapshot ?? { children: [] },
    createdAt: draft.createdAt?.toISOString() ?? null,
    updatedAt: draft.updatedAt?.toISOString() ?? null,
  };
}

export function mapFlowBoardDraftSummary(draft: FlowBoardDraft) {
  return {
    id: draft.id,
    title: draft.title || "未命名流程白板",
    createdAt: draft.createdAt?.toISOString() ?? null,
    updatedAt: draft.updatedAt?.toISOString() ?? null,
  };
}