import type { FlowchartUpdate } from "@oj2/contract"
import { eq } from "drizzle-orm"

import { config } from "../config"
import { db, schema } from "../db"
import { publishFlowchartUpdate } from "../events"
import { completeChat } from "../services/ai"
import type { FlowchartJobData } from "./job"

function evaluationPrompt(problem: typeof schema.problem.$inferSelect) {
  return `你是专业的编程教学助手，负责评估学生的 Mermaid 流程图。
评分：逻辑正确性40分、完整性30分、规范性20分、清晰度10分。
不要评价系统生成的节点ID。feedback不超过100字；suggestions最多3条且只针对真实问题。
返回纯 JSON：{"score":85,"grade":"A","feedback":"...","suggestions":"...","criteria_details":{}}。
等级：S=90-100，A=80-89，B=70-79，C=0-69。
题目：${problem.title}\n${problem.description.slice(0, 2000)}`
}

/**
 * 等级一律由分数推出来，不采信模型自报的 grade。
 * 提示词里写死了这四档，但模型偶尔会给出 88 分配 S 级这种自相矛盾的结果，
 * 甚至直接吐「优秀」；脏值会一路串到等级分布图和「A/S 才展示流程图」的判断里。
 */
function gradeForScore(score: number) {
  if (score >= 90) return "S"
  if (score >= 80) return "A"
  if (score >= 70) return "B"
  return "C"
}

function parseEvaluation(value: string) {
  const block = value.match(/```(?:json)?\s*([\s\S]*?)```/)?.[1]
  const json = block ?? value.match(/\{[\s\S]*\}/)?.[0]
  if (!json) throw new Error("AI response did not contain JSON")
  const data = JSON.parse(json) as Record<string, unknown>
  if (typeof data.score !== "number" || Number.isNaN(data.score))
    throw new Error("AI response is missing score")
  const score = Math.max(0, Math.min(100, data.score))
  return {
    score,
    grade: gradeForScore(score),
    feedback: typeof data.feedback === "string" ? data.feedback : "",
    suggestions: typeof data.suggestions === "string" ? data.suggestions : "",
    criteria:
      data.criteria_details && typeof data.criteria_details === "object"
        ? data.criteria_details
        : {},
  }
}

export async function evaluateFlowchart(
  job: FlowchartJobData,
  { isFinalAttempt = true }: { isFinalAttempt?: boolean } = {},
) {
  const [row] = await db
    .select({ flowchart: schema.flowchartSubmission, problem: schema.problem })
    .from(schema.flowchartSubmission)
    .innerJoin(schema.problem, eq(schema.flowchartSubmission.problemId, schema.problem.id))
    .where(eq(schema.flowchartSubmission.id, job.submissionId))
    .limit(1)
  if (!row || ![0, 1].includes(row.flowchart.status)) return
  await db
    .update(schema.flowchartSubmission)
    .set({ status: 1 })
    .where(eq(schema.flowchartSubmission.id, row.flowchart.id))
  const started = performance.now()
  try {
    const reference = row.problem.mermaidCode
      ? `\n标准答案参考：\n${row.problem.mermaidCode}`
      : "\n此题没有标准流程图。"
    const result = parseEvaluation(
      await completeChat(
        evaluationPrompt(row.problem),
        `学生流程图：\n${row.flowchart.mermaidCode}${reference}\n设计提示：${row.problem.flowchartHint ?? "无"}`,
      ),
    )
    await db
      .update(schema.flowchartSubmission)
      .set({
        status: 2,
        aiScore: result.score,
        aiGrade: result.grade,
        aiFeedback: result.feedback,
        aiSuggestions: result.suggestions,
        aiCriteriaDetails: result.criteria,
        aiProvider: config.aiProvider,
        aiModel: config.aiModel,
        processingTime: (performance.now() - started) / 1000,
        evaluationTime: new Date().toISOString(),
      })
      .where(eq(schema.flowchartSubmission.id, row.flowchart.id))
    await publishFlowchartUpdate(row.flowchart.userId, {
      type: "flowchart_evaluation_completed",
      submissionId: row.flowchart.id,
      score: result.score,
      grade: result.grade,
      feedback: result.feedback,
      suggestions: result.suggestions,
      criteriaDetails: result.criteria,
    } satisfies FlowchartUpdate)
  } catch (error) {
    // 原来这里把 error.message 原样推给学生、前端还直接 message.error 弹出来 ——
    // AI provider 的地址、内部报错就这么进了浏览器。真实原因留在服务端日志里，
    // 学生只需要知道「失败了，再试一次」；error 字段留空，前端有兜底文案。
    console.error(`Failed to evaluate flowchart ${row.flowchart.id}`, error)
    // 只有最后一次尝试才落 FAILED。中间几次必须把状态留在 PROCESSING(1)：
    // 上面那道 `![0, 1].includes(status)` 的守卫会把状态为 3 的任务直接放行返回，
    // 一旦提前写成 3，队列配的 attempts: 3 就成了摆设 —— 后两次尝试进来什么都不做
    // 就算成功，AI 侧的偶发失败（限流、超时、网络抖动）永远等不到重试。
    if (!isFinalAttempt) throw error
    await db
      .update(schema.flowchartSubmission)
      .set({ status: 3 })
      .where(eq(schema.flowchartSubmission.id, row.flowchart.id))
    await publishFlowchartUpdate(row.flowchart.userId, {
      type: "flowchart_evaluation_failed",
      submissionId: row.flowchart.id,
    } satisfies FlowchartUpdate)
    throw error
  }
}