import { ZodError } from "zod";
import {
  canApplyCanvasAgentMutations,
  type CanvasAgentFeatureFlags,
} from "@/lib/canvas/agent-feature-flags";
import {
  CanvasAgentMutationError,
  type CanvasOperationResult,
} from "@/lib/canvas/agent-mutations";
import { parseCanvasAgentOperationRequestBody } from "@/lib/canvas/agent-operation-request";
import type { CanvasOperationPlan } from "@/types/canvas/agent-protocol";

export type CanvasAgentOperationRouteBody =
  | {
      success: true;
      data: CanvasOperationResult;
    }
  | {
      success: false;
      error: string;
      code?: string;
      writebackMode?: CanvasAgentFeatureFlags["writebackMode"];
      details?: unknown;
    };

export type CanvasAgentOperationRouteResponse = {
  status: number;
  body: CanvasAgentOperationRouteBody;
};

export async function handleCanvasAgentOperationRouteRequest(params: {
  userId?: string | null;
  projectId: string;
  rawBody?: unknown;
  readBody?: () => Promise<unknown>;
  features: CanvasAgentFeatureFlags;
  applyOperation: (input: {
    userId: string;
    projectId: string;
    plan: CanvasOperationPlan;
  }) => Promise<CanvasOperationResult>;
  logger?: Pick<Console, "error">;
}): Promise<CanvasAgentOperationRouteResponse> {
  const userId = String(params.userId || "").trim();
  if (!userId) {
    return {
      status: 401,
      body: { success: false, error: "未登录" },
    };
  }

  if (!canApplyCanvasAgentMutations(params.features)) {
    return {
      status: 409,
      body: {
        success: false,
        error: "当前画布 Agent 写回处于灰度保护，未修改画布",
        code: "CANVAS_AGENT_WRITEBACK_DISABLED",
        writebackMode: params.features.writebackMode,
      },
    };
  }

  try {
    const rawBody = params.readBody ? await params.readBody() : params.rawBody;
    const body = parseCanvasAgentOperationRequestBody(rawBody);
    const planProjectId = String(body.operationPlan.projectId || "").trim();
    if (planProjectId && planProjectId !== params.projectId) {
      return {
        status: 400,
        body: {
          success: false,
          error: "operation projectId 与请求项目不一致",
          code: "CANVAS_AGENT_PROJECT_MISMATCH",
        },
      };
    }
    const operationPlan: CanvasOperationPlan = {
      ...body.operationPlan,
      projectId: planProjectId || params.projectId,
    };
    const result = await params.applyOperation({
      userId,
      projectId: params.projectId,
      plan: operationPlan,
    });

    return {
      status: 200,
      body: {
        success: true,
        data: result,
      },
    };
  } catch (error) {
    if (error instanceof CanvasAgentMutationError) {
      return {
        status: error.status,
        body: {
          success: false,
          error: error.message,
          code: error.code,
        },
      };
    }
    if (error instanceof ZodError) {
      return {
        status: 400,
        body: {
          success: false,
          error: "请求参数无效",
          details: error.flatten(),
        },
      };
    }
    if (error instanceof SyntaxError) {
      return {
        status: 400,
        body: { success: false, error: "请求 JSON 无效" },
      };
    }

    params.logger?.error("[CanvasAgentOperations] apply operation failed:", error);
    return {
      status: 500,
      body: { success: false, error: "执行画布操作失败" },
    };
  }
}