import { query, mutation } from "./_generated/server";
import { v } from "convex/values";
import type { GenericQueryCtx } from "convex/server";
import type { DataModel, Id } from "./_generated/dataModel";
import { hasPermission, getRolesForUser } from "./roles";
import { AUDIT_ACTIONS, logAudit } from "./audit";
import { getPublicStorageUrl } from "./storageUrl";

/**
 * Returns true if the user is currently banned. Callers should
 * surface this as an explicit `{ error: "Banned" }` at auth time or
 * throw from sensitive mutations like `messages.send`.
 */
export async function isBanned(
  ctx: GenericQueryCtx<DataModel>,
  userId: Id<"userProfiles">,
): Promise<boolean> {
  const row = await ctx.db
    .query("bans")
    .withIndex("by_user", (q) => q.eq("userId", userId))
    .first();
  return !!row;
}

export const isUserBanned = query({
  args: { userId: v.id("userProfiles") },
  returns: v.boolean(),
  handler: async (ctx, args) => isBanned(ctx, args.userId),
});

// List all bans with actor + target enrichment for the Bans tab.
export const list = query({
  args: { actorId: v.id("userProfiles") },
  returns: v.array(v.any()),
  handler: async (ctx, args) => {
    if (!(await hasPermission(ctx, args.actorId, "ban_members"))) {
      throw new Error("You don't have permission to view bans.");
    }
    const bans = await ctx.db.query("bans").collect();
    const out = [];
    for (const b of bans) {
      const user = await ctx.db.get(b.userId);
      const actor = await ctx.db.get(b.bannedBy);
      let avatarUrl: string | null = null;
      if (user?.avatarStorageId) {
        avatarUrl = await getPublicStorageUrl(ctx, user.avatarStorageId);
      }
      out.push({
        _id: b._id,
        userId: b.userId,
        bannedBy: b.bannedBy,
        reason: b.reason ?? null,
        createdAt: b.createdAt,
        user: user
          ? {
              username: user.username,
              displayName: user.displayName,
              avatarUrl,
            }
          : null,
        actor: actor
          ? { username: actor.username, displayName: actor.displayName }
          : null,
      });
    }
    out.sort((a, b) => b.createdAt - a.createdAt);
    return out;
  },
});

export const ban = mutation({
  args: {
    actorId: v.id("userProfiles"),
    userId: v.id("userProfiles"),
    reason: v.optional(v.string()),
  },
  returns: v.object({ success: v.boolean() }),
  handler: async (ctx, args) => {
    if (!(await hasPermission(ctx, args.actorId, "ban_members"))) {
      throw new Error("You don't have permission to ban members.");
    }
    if (args.actorId === args.userId) {
      throw new Error("You can't ban yourself.");
    }
    const target = await ctx.db.get(args.userId);
    if (!target) throw new Error("User not found.");

    // Refuse to ban isAdmin or Owner-role bearers. Single-server
    // deployment can't afford to lock itself out of administration.
    if (target.isAdmin) {
      throw new Error("Server admins can't be banned.");
    }
    const targetRoles = await getRolesForUser(ctx, args.userId);
    if (targetRoles.some((r) => r.name === "Owner")) {
      throw new Error("The Owner can't be banned.");
    }

    const existing = await ctx.db
      .query("bans")
      .withIndex("by_user", (q) => q.eq("userId", args.userId))
      .first();
    if (existing) {
      // Update reason + actor if re-banning.
      await ctx.db.patch(existing._id, {
        bannedBy: args.actorId,
        reason: args.reason,
        createdAt: Date.now(),
      });
    } else {
      await ctx.db.insert("bans", {
        userId: args.userId,
        bannedBy: args.actorId,
        reason: args.reason,
        createdAt: Date.now(),
      });
    }

    await logAudit(ctx, {
      actorId: args.actorId,
      action: AUDIT_ACTIONS.BAN_ADD,
      targetType: "user",
      targetId: args.userId,
      targetName: target.displayName ?? target.username,
      metadata: args.reason ? { reason: args.reason } : undefined,
    });

    return { success: true };
  },
});

export const unban = mutation({
  args: {
    actorId: v.id("userProfiles"),
    userId: v.id("userProfiles"),
  },
  returns: v.object({ success: v.boolean() }),
  handler: async (ctx, args) => {
    if (!(await hasPermission(ctx, args.actorId, "ban_members"))) {
      throw new Error("You don't have permission to unban members.");
    }
    const row = await ctx.db
      .query("bans")
      .withIndex("by_user", (q) => q.eq("userId", args.userId))
      .first();
    if (!row) return { success: true };

    const target = await ctx.db.get(args.userId);
    await ctx.db.delete(row._id);

    await logAudit(ctx, {
      actorId: args.actorId,
      action: AUDIT_ACTIONS.BAN_REMOVE,
      targetType: "user",
      targetId: args.userId,
      targetName: target?.displayName ?? target?.username,
    });

    return { success: true };
  },
});