import { z } from "zod";
import type { SerializedWidgetMeta } from "@/modules/_core/registry";

export type WidgetPlacement = {
  widgetId: string;
  config: unknown;
  x: number;
  y: number;
  w: number;
  h: number;
};

export function widgetContentKey(placement: Pick<WidgetPlacement, "widgetId" | "config">): string {
  return `${placement.widgetId}::${JSON.stringify(placement.config)}`;
}

export type DashboardLayout = {
  version: 1;
  widgets: WidgetPlacement[];
};

const placementSchema = z.object({
  widgetId: z.string(),
  config: z.unknown(),
  x: z.number().int().min(0),
  y: z.number().int().min(0),
  w: z.number().int().min(1).max(12),
  h: z.number().int().min(1),
});

const layoutSchema = z.object({
  version: z.literal(1),
  widgets: z.array(placementSchema),
});

export function parseDashboardLayout(raw: unknown): DashboardLayout | null {
  const result = layoutSchema.safeParse(raw);
  if (!result.success) return null;
  return result.data;
}

export type PresetId = "classic" | "split" | "glance";

/** Client-safe layout builder: pass the metas explicitly. The server-only
 *  variants (`computePresetLayout`, `computeDefaultLayout`) live in
 *  `dashboard.server.ts` because they reach into the module registry. */
export function computePresetLayoutFromMetas(
  preset: PresetId,
  metas: SerializedWidgetMeta[],
): DashboardLayout {
  switch (preset) {
    case "classic":
      return classicLayout(metas);
    case "split":
      return splitLayout(metas);
    case "glance":
      return glanceLayout(metas);
  }
}

function classicLayout(metas: SerializedWidgetMeta[]): DashboardLayout {
  const placements: WidgetPlacement[] = [];
  let mainY = 0;
  let railY = 0;

  metas.forEach((m, i) => {
    const inRail = i % 3 === 0 && i > 0;
    if (inRail) {
      placements.push({
        widgetId: m.id,
        config: m.defaultConfig,
        x: 8,
        y: railY,
        w: 4,
        h: m.defaultSize.h,
      });
      railY += m.defaultSize.h;
    } else {
      placements.push({
        widgetId: m.id,
        config: m.defaultConfig,
        x: 0,
        y: mainY,
        w: 8,
        h: m.defaultSize.h,
      });
      mainY += m.defaultSize.h;
    }
  });

  return { version: 1, widgets: placements };
}

function splitLayout(metas: SerializedWidgetMeta[]): DashboardLayout {
  const placements: WidgetPlacement[] = [];
  let leftY = 0;
  let rightY = 0;

  metas.forEach((m, i) => {
    const left = i % 2 === 0;
    if (left) {
      placements.push({
        widgetId: m.id,
        config: m.defaultConfig,
        x: 0,
        y: leftY,
        w: 6,
        h: m.defaultSize.h,
      });
      leftY += m.defaultSize.h;
    } else {
      placements.push({
        widgetId: m.id,
        config: m.defaultConfig,
        x: 6,
        y: rightY,
        w: 6,
        h: m.defaultSize.h,
      });
      rightY += m.defaultSize.h;
    }
  });

  return { version: 1, widgets: placements };
}

function glanceLayout(metas: SerializedWidgetMeta[]): DashboardLayout {
  const placements: WidgetPlacement[] = [];
  let y = 0;
  metas.forEach((m) => {
    placements.push({
      widgetId: m.id,
      config: m.defaultConfig,
      x: 0,
      y,
      w: 12,
      h: m.defaultSize.h,
    });
    y += m.defaultSize.h;
  });
  return { version: 1, widgets: placements };
}