import { randomBytes } from "node:crypto"
import { extname, resolve } from "node:path"

import {
  rankProfileSchema,
  registerRequestSchema,
  STUDENT_ROLES,
  updateProfileRequestSchema,
  type ActivityRankItem,
  type Metrics,
  type MyRank,
  type ProblemRank,
  type RankProfile,
  type UserRank,
  type WeeklyRank,
  type WeeklyRankItem,
} from "@oj2/contract"
import {
  and,
  asc,
  count,
  countDistinct,
  desc,
  eq,
  gt,
  gte,
  inArray,
  isNull,
  lt,
  lte,
  max,
  min,
  ne,
  notExists,
  or,
  sql,
} from "drizzle-orm"
import { alias } from "drizzle-orm/pg-core"
import { Hono } from "hono"

import { hashPassword } from "../auth/password"
import { onlineUserIds } from "../auth/presence"
import { optionalAuth, requireAuth, type AppEnv } from "../auth/middleware"
import { config } from "../config"
import { db, schema } from "../db"
import { failure, success } from "../http"
import { JudgeStatus } from "../judge/status"
import { getBooleanOption } from "../services/options"
import { getUserProfileById } from "../services/profile"
import { localTime, weekStart } from "../time"
import {
  isTeacherOrAbove,
  objectValue,
  queryInteger,
  sampleUser,
} from "./helpers"

export const accountRoutes = new Hono<AppEnv>()

accountRoutes.post("/users", async (c) => {
  const parsed = registerRequestSchema.safeParse(
    await c.req.json().catch(() => null),
  )
  if (!parsed.success)
    return failure(c, 400, "invalid-request", "Invalid registration payload")
  if (!(await getBooleanOption("allow_register", true))) {
    return failure(
      c,
      403,
      "registration-disabled",
      "Register function has been disabled by admin",
    )
  }

  const username = parsed.data.username.toLowerCase()
  const email = parsed.data.email.toLowerCase()
  const [duplicate] = await db
    .select({ username: schema.user.username, email: schema.user.email })
    .from(schema.user)
    .where(
      or(
        sql`lower(${schema.user.username}) = ${username}`,
        sql`lower(${schema.user.email}) = ${email}`,
      ),
    )
    .limit(1)
  if (duplicate?.username.toLowerCase() === username) {
    return failure(c, 409, "username-exists", "Username already exists")
  }
  if (duplicate?.email?.toLowerCase() === email) {
    return failure(c, 409, "email-exists", "Email already exists")
  }

  const now = new Date().toISOString()
  const password = await hashPassword(parsed.data.password)
  await db.transaction(async (tx) => {
    const [created] = await tx
      .insert(schema.user)
      .values({
        username,
        email,
        password,
        rawPassword: parsed.data.password.slice(0, 20),
        lastLogin: null,
        createTime: now,
        adminType: "Regular User",
        isDisabled: false,
        problemPermission: "None",
        className: null,
      })
      .returning({ id: schema.user.id })
    if (!created) throw new Error("User insert did not return an id")
    await tx.insert(schema.userProfile).values({
      userId: created.id,
      acmProblemsStatus: {},
      avatar: `${config.avatarUriPrefix}/default.png`,
      mood: null,
      acceptedNumber: 0,
      submissionNumber: 0,
      realName: null,
    })
  })
  return success(c, { ok: true }, 201)
})

accountRoutes.get("/profiles/:username", optionalAuth, async (c) => {
  // 对齐旧后端 account/views/oj.py 的 UserProfileAPI.get 首行：
  // `if not user.is_authenticated: return self.success()` —— 匿名一律返回空，
  // 否则用户名可经 /rankings/users 公开枚举，进而无 cookie 批量收集全校学生的邮箱与最后登录时间。
  if (!c.get("user")) return success(c, null)
  const [target] = await db
    .select({ id: schema.user.id })
    .from(schema.user)
    .where(
      and(
        sql`lower(${schema.user.username}) = lower(${c.req.param("username")})`,
        eq(schema.user.isDisabled, false),
      ),
    )
    .limit(1)
  if (!target) return failure(c, 404, "user-not-found", "User does not exist")
  const profile = await getUserProfileById(
    target.id,
    c.get("user")?.id === target.id,
  )
  if (!profile)
    return failure(c, 404, "profile-not-found", "User profile does not exist")
  return success(c, profile)
})

accountRoutes.put("/me/profile", requireAuth, async (c) => {
  const parsed = updateProfileRequestSchema.safeParse(
    await c.req.json().catch(() => null),
  )
  if (!parsed.success)
    return failure(c, 400, "invalid-request", "Invalid profile payload")
  const values = Object.fromEntries(
    Object.entries(parsed.data).map(([key, value]) => [
      key,
      value === "" ? null : value,
    ]),
  )
  await db
    .update(schema.userProfile)
    .set(values)
    .where(eq(schema.userProfile.userId, c.get("user")!.id))
  const profile = await getUserProfileById(c.get("user")!.id, true)
  if (!profile)
    return failure(c, 404, "profile-not-found", "User profile does not exist")
  return success(c, profile)
})

accountRoutes.post("/me/avatar", requireAuth, async (c) => {
  const body: Record<string, string | File> = await c.req
    .parseBody()
    .catch(() => ({}))
  const image = body.image
  if (!(image instanceof File))
    return failure(c, 400, "invalid-file", "Invalid file content")
  if (image.size > 2 * 1024 * 1024)
    return failure(c, 400, "file-too-large", "Picture is too large")
  const extension = extname(image.name).toLowerCase()
  if (![".gif", ".jpg", ".jpeg", ".bmp", ".png"].includes(extension)) {
    return failure(c, 400, "unsupported-file", "Unsupported file format")
  }
  const filename = `${randomBytes(10).toString("hex")}${extension}`
  const directory = resolve(config.avatarDirectory)
  await Bun.$`mkdir -p ${directory}`.quiet()
  await Bun.write(resolve(directory, filename), image)
  const avatar = `${config.avatarUriPrefix}/${filename}`
  await db
    .update(schema.userProfile)
    .set({ avatar })
    .where(eq(schema.userProfile.userId, c.get("user")!.id))
  return success(c, { avatar })
})

accountRoutes.get("/users/:id/metrics", async (c) => {
  const userId = queryInteger(c.req.param("id"), 0, { min: 1 })
  // 比赛提交也算：首末提交时间、学习天数都连比赛一起统计
  const [row] = await db
    .select({
      first: min(schema.submission.createTime),
      latest: max(schema.submission.createTime),
      activeDays: countDistinct(
        sql`date(${localTime(schema.submission.createTime)})`,
      ),
    })
    .from(schema.submission)
    .where(eq(schema.submission.userId, userId))
  if (!row?.first || !row.latest)
    return failure(c, 404, "no-submissions", "暂无提交")
  return success(c, {
    now: new Date().toISOString(),
    first: row.first,
    latest: row.latest,
    activeDays: row.activeDays,
  } satisfies Metrics)
})

/**
 * 全服榜单的大小。**写死在服务端，不接受调用方传** —— 上限是这个端点的属性，
 * 不是调用方的选择。
 *
 * 之前它是个 `top` 查询参数，三个调用方各传各的（100 / 10 / 0），
 * 而 top 又会覆盖 limit 与 offset，total 却按全量人数算 —— 于是分页器算出几十页、
 * 页页内容相同（36e4ac2）。「全服 Top10」不需要另一个上限，取 limit=10&offset=0 即可；
 * 后台那个「不限量」的用法搬去了 /admin/rankings/users。
 */
const LEADERBOARD_SIZE = 100

/** 入榜人群：正常状态的学生与学生管理员。教师和超管不参与排名。 */
const leaderboardWhere = and(
  inArray(schema.user.adminType, [...STUDENT_ROLES]),
  eq(schema.user.isDisabled, false),
)

/**
 * 榜单排序：AC 多的在前 → 同 AC 时提交少的在前 → 再同就按 id。
 *
 * 第三档不是凑数：前两个键完全相同的学生在真实数据里成片存在（都是 0/0），
 * 没有稳定的兜底键时 postgres 每次返回的顺序可以不同，翻页会看到重复或漏掉的人。
 */
const leaderboardOrder = [
  desc(schema.userProfile.acceptedNumber),
  asc(schema.userProfile.submissionNumber),
  asc(schema.user.id),
]

accountRoutes.get("/rankings/users", optionalAuth, async (c) => {
  const limit = queryInteger(c.req.query("limit"), 10, {
    min: 1,
    max: LEADERBOARD_SIZE,
  })
  const offset = queryInteger(c.req.query("offset"), 0, { min: 0 })

  // 榜单封顶 100 名，所以这一页最多还能取几条只取决于 offset，**不取决于总人数** ——
  // 真人不够时数据库自己会少返回。不拿 total 当上限，三段查询就能并发发出去，
  // 端点延迟从「四个来回相加」变成「最慢的那个」。越界页一条不剩，直接不发 SQL。
  const pageLimit = Math.max(0, Math.min(limit, LEADERBOARD_SIZE - offset))

  // 谁在线只给老师看，学生那边整列都是 null（见 rankProfileSchema.isOnline）
  const [totalRow, rows, me, online] = await Promise.all([
    db
      .select({ value: count() })
      .from(schema.userProfile)
      .innerJoin(schema.user, eq(schema.userProfile.userId, schema.user.id))
      .where(leaderboardWhere)
      .then(([row]) => row),
    pageLimit === 0
      ? []
      : db
          .select({ profile: schema.userProfile, user: schema.user })
          .from(schema.userProfile)
          .innerJoin(schema.user, eq(schema.userProfile.userId, schema.user.id))
          .where(leaderboardWhere)
          .orderBy(...leaderboardOrder)
          .limit(pageLimit)
          .offset(offset),
    myLeaderboardRank(c.get("user")?.id),
    isTeacherOrAbove(c.get("user")) ? onlineUserIds() : null,
  ])

  return success(c, {
    results: rows.map((row) => serializeRankRow(row, online)),
    total: Math.min(totalRow?.value ?? 0, LEADERBOARD_SIZE),
    me,
  } satisfies UserRank)
})

function serializeRankRow(
  {
    profile,
    user,
  }: {
    profile: typeof schema.userProfile.$inferSelect
    user: typeof schema.user.$inferSelect
  },
  online: Set<number> | null = null,
) {
  return {
    id: profile.id,
    user: sampleUser(user, profile.realName),
    acceptedNumber: profile.acceptedNumber,
    submissionNumber: profile.submissionNumber,
    mood: profile.mood,
    isOnline: online ? online.has(user.id) : null,
  } satisfies RankProfile
}

/**
 * 「我」的全服名次，登录且身份入榜时才有。
 *
 * 名次 = 排在我前面的人数 + 1，三个排序键**逐级**比较，与列表的 orderBy 逐字对应 ——
 * 少比一级就会出现「显示第 7 名、实际排在表格第 9 行」这种对不上的情况。
 * 三个键全等才算并列，此时名次相同。
 */
async function myLeaderboardRank(userId: number | undefined) {
  if (!userId) return null
  const [mine] = await db
    .select({ profile: schema.userProfile, user: schema.user })
    .from(schema.userProfile)
    .innerJoin(schema.user, eq(schema.userProfile.userId, schema.user.id))
    .where(and(leaderboardWhere, eq(schema.user.id, userId)))
    .limit(1)
  if (!mine) return null

  const { acceptedNumber, submissionNumber } = mine.profile
  const [ahead] = await db
    .select({ value: count() })
    .from(schema.userProfile)
    .innerJoin(schema.user, eq(schema.userProfile.userId, schema.user.id))
    .where(
      and(
        leaderboardWhere,
        or(
          gt(schema.userProfile.acceptedNumber, acceptedNumber),
          and(
            eq(schema.userProfile.acceptedNumber, acceptedNumber),
            lt(schema.userProfile.submissionNumber, submissionNumber),
          ),
          and(
            eq(schema.userProfile.acceptedNumber, acceptedNumber),
            eq(schema.userProfile.submissionNumber, submissionNumber),
            lt(schema.user.id, userId),
          ),
        ),
      ),
    )

  return {
    ...serializeRankRow(mine),
    rank: (ahead?.value ?? 0) + 1,
  } satisfies MyRank
}

accountRoutes.get("/rankings/activity", async (c) => {
  const start = c.req.query("start")
  if (!start || Number.isNaN(Date.parse(start)))
    return failure(c, 400, "invalid-start", "start time is required")
  /**
   * 按 **user_id** 聚合，名字从 user 表取。按 `submission.username` 分组的话，
   * 改过名的学生会裂成新旧两条各算各的 AC 题数 —— 排名被拆低，运气不好还会以
   * 两个名字同时挂在榜上。同 `/submissions/statistics` 那批。
   *
   * innerJoin user 顺带把已删号学生的孤儿提交挡在外面，不用再兜底名字。
   */
  const rows = await db
    .select({
      username: schema.user.username,
      value: countDistinct(schema.submission.problemId),
    })
    .from(schema.submission)
    .innerJoin(schema.user, eq(schema.submission.userId, schema.user.id))
    .where(
      and(
        isNull(schema.submission.contestId),
        gte(schema.submission.createTime, start),
        inArray(schema.submission.result, [
          JudgeStatus.ACCEPTED,
          JudgeStatus.AST_CHECK_FAILED,
        ]),
        eq(schema.user.isDisabled, false),
        ne(schema.user.adminType, "Super Admin"),
      ),
    )
    .groupBy(schema.submission.userId, schema.user.username)
    .orderBy(desc(countDistinct(schema.submission.problemId)))
    .limit(10)
  return success(
    c,
    rows.map(
      (row) =>
        ({
          username: row.username,
          count: row.value,
        }) satisfies ActivityRankItem,
    ),
  )
})

/**
 * 周榜的榜面大小。**存量榜（`/rankings/users`）解决的是「谁最强」，周榜解决的是
 * 「这一周谁在往前走」** —— 后者每周一清零，所以榜面短一点更像「这周的头名」，
 * 长了反而又变成一张追不上的总表。榜外的人靠 `me` 单独看到自己的名次。
 */
const WEEKLY_BOARD_SIZE = 10

/** 算「解决」的两个状态：AST_CHECK_FAILED 也是答案对了，与 /rankings/activity 同口径 */
const ACCEPTED_RESULTS = [JudgeStatus.ACCEPTED, JudgeStatus.AST_CHECK_FAILED]

/**
 * 本周进步榜：按**本周首次 AC 的题目数**排名，每周一 0:00（东八区）清零。
 *
 * 和 `/rankings/users` 的区别不只是加了时间窗：那张榜排的是 `user_profile` 的存量
 * AC 总数，名次几乎不动，中位学生看一眼就知道追不上，等于负反馈。这张榜的分母是
 * 「这一周」，谁都可能进前十。
 *
 * 「首次 AC」是靠 NOT EXISTS 排掉本周之前已经通过过的 (user, problem) 对，不是简单
 * 数本周 AC 的去重题数 —— 后者把老题重交一遍也算成绩，一分钟能刷满一屏。
 * 相关子查询的四个条件正好是 `submission_public_metrics_idx`
 * （user_id, problem_id, result, create_time，WHERE contest_id IS NULL）的全部列，
 * 而且外层已经把行数收在「本周的 AC」这一小撮上，不会退化成按人全表回查。
 */
accountRoutes.get("/rankings/weekly", optionalAuth, async (c) => {
  const user = c.get("user")
  const scope = c.req.query("scope") === "class" ? "class" : "global"
  const className = scope === "class" ? (user?.className ?? null) : null
  if (scope === "class" && !className)
    return failure(c, 400, "class-missing", "用户没有班级信息")

  const start = weekStart()

  // 入榜人群与全服榜一致（leaderboardWhere）：正常状态的学生与学生管理员
  const audience = and(
    inArray(schema.user.adminType, [...STUDENT_ROLES]),
    eq(schema.user.isDisabled, false),
    className ? eq(schema.user.className, className) : undefined,
  )
  const thisWeek = and(
    isNull(schema.submission.contestId),
    gte(schema.submission.createTime, start),
    audience,
  )

  const earlier = alias(schema.submission, "earlier")
  const [solvedRows, submittedRows] = await Promise.all([
    db
      .select({
        userId: schema.submission.userId,
        username: schema.user.username,
        value: countDistinct(schema.submission.problemId),
      })
      .from(schema.submission)
      .innerJoin(schema.user, eq(schema.user.id, schema.submission.userId))
      .where(
        and(
          thisWeek,
          inArray(schema.submission.result, ACCEPTED_RESULTS),
          notExists(
            db
              .select({ one: sql`1` })
              .from(earlier)
              .where(
                and(
                  eq(earlier.userId, schema.submission.userId),
                  eq(earlier.problemId, schema.submission.problemId),
                  isNull(earlier.contestId),
                  inArray(earlier.result, ACCEPTED_RESULTS),
                  lt(earlier.createTime, start),
                ),
              ),
          ),
        ),
      )
      .groupBy(schema.submission.userId, schema.user.username),
    db
      .select({ userId: schema.submission.userId, value: count() })
      .from(schema.submission)
      .innerJoin(schema.user, eq(schema.user.id, schema.submission.userId))
      .where(thisWeek)
      .groupBy(schema.submission.userId),
  ])

  const submissions = new Map(
    submittedRows.map((row) => [row.userId, row.value]),
  )
  /**
   * 排序键与全服榜同构：解决多的在前 → 同解决数时提交少的在前 → 再同按 id。
   * 第三档同样不是凑数，周榜上「都是 1 题」的学生成片存在，没有稳定兜底键时
   * postgres 每次返回的顺序可以不同，刷新一下名次就变了。
   */
  const ranked = solvedRows
    .sort(
      (a, b) =>
        b.value - a.value ||
        (submissions.get(a.userId) ?? 0) - (submissions.get(b.userId) ?? 0) ||
        a.userId - b.userId,
    )
    .map(
      (row, index) =>
        ({
          user: sampleUser({ id: row.userId, username: row.username }, null),
          solvedCount: row.value,
          submissionCount: submissions.get(row.userId) ?? 0,
          rank: index + 1,
        }) satisfies WeeklyRankItem,
    )

  return success(c, {
    start,
    scope,
    className,
    total: ranked.length,
    results: ranked.slice(0, WEEKLY_BOARD_SIZE),
    me: ranked.find((row) => row.user.id === user?.id) ?? null,
  } satisfies WeeklyRank)
})

accountRoutes.get("/problems/:displayId/rank", requireAuth, async (c) => {
  const user = c.get("user")!
  const [problem] = await db
    .select({ id: schema.problem.id })
    .from(schema.problem)
    .where(
      and(
        sql`lower(${schema.problem.displayId}) = lower(${c.req.param("displayId")})`,
        isNull(schema.problem.contestId),
        eq(schema.problem.visible, true),
      ),
    )
    .limit(1)
  if (!problem)
    return failure(c, 404, "problem-not-found", "Problem does not exist")
  const accepted = and(
    eq(schema.submission.problemId, problem.id),
    inArray(schema.submission.result, [0, 10]),
  )
  const [all] = await db
    .select({ value: countDistinct(schema.submission.userId) })
    .from(schema.submission)
    .where(accepted)
  const className = user.className ?? ""
  const classWhere = className
    ? and(
        accepted,
        inArray(
          schema.submission.userId,
          db
            .select({ id: schema.user.id })
            .from(schema.user)
            .where(
              and(
                eq(schema.user.className, className),
                eq(schema.user.isDisabled, false),
              ),
            ),
        ),
      )
    : accepted
  const [classCount] = className
    ? await db
        .select({ value: countDistinct(schema.submission.userId) })
        .from(schema.submission)
        .where(classWhere)
    : [{ value: 0 }]
  const [first] = await db
    .select({ value: min(schema.submission.createTime) })
    .from(schema.submission)
    .where(and(classWhere, eq(schema.submission.userId, user.id)))
  let rank = -1
  if (first?.value) {
    const [rankRow] = await db
      .select({ value: count() })
      .from(schema.submission)
      .where(and(classWhere, lte(schema.submission.createTime, first.value)))
    rank = rankRow?.value ?? -1
  }
  return success(c, {
    className,
    rank,
    classAcCount: classCount?.value ?? 0,
    allAcCount: all?.value ?? 0,
  } satisfies ProblemRank)
})

/**
 * 把 `user_profile.acm_problems_status` 里缓存的题目编号刷成当前值 ——
 * 教师改了题目的 `_id`（后台「修改题目编号」）之后，学生个人主页上的那份缓存会变旧。
 *
 * **目前没有任何前端在调用它**，两代前端都只定义了函数、没有调用点。保留是因为
 * 它是唯一能修这份缓存的入口；要接 UI 的话，从这里开始。
 *
 * 旧后端 `ProfileProblemDisplayIDRefreshAPI` 这段是坏的：它用
 * `dict(zip(ids, display_ids))` 把「dict 键顺序」和「查询返回顺序」硬凑成对，
 * 题目一旦被隐藏或删除，display_ids 就比 ids 短 —— 轻则把编号张冠李戴写进库，
 * 重则 `id_map[k]` KeyError。这里改成按 id 建 Map、查不到就不动。
 */
accountRoutes.post(
  "/me/problem-display-ids/refresh",
  requireAuth,
  async (c) => {
    const user = c.get("user")!
    const [profile] = await db
      .select({ value: schema.userProfile.acmProblemsStatus })
      .from(schema.userProfile)
      .where(eq(schema.userProfile.userId, user.id))
      .limit(1)
    const status = objectValue(profile?.value)
    const problems = objectValue(status.problems)
    const ids = Object.keys(problems).map(Number).filter(Number.isInteger)
    if (ids.length > 0) {
      const rows = await db
        .select({ id: schema.problem.id, displayId: schema.problem.displayId })
        .from(schema.problem)
        .where(
          and(
            inArray(schema.problem.id, ids),
            eq(schema.problem.visible, true),
          ),
        )
      const displayIds = new Map(
        rows.map((row) => [String(row.id), row.displayId]),
      )
      for (const [id, value] of Object.entries(problems)) {
        const item = objectValue(value)
        const displayId = displayIds.get(id)
        if (displayId) item._id = displayId
        problems[id] = item
      }
      status.problems = problems
      await db
        .update(schema.userProfile)
        .set({ acmProblemsStatus: status })
        .where(eq(schema.userProfile.userId, user.id))
    }
    return success(c, null)
  },
)