import { z } from "zod";

import { isHttpsUrl, ITEM_KINDS, parseYouTube } from "@/lib/screen";
import { idSchema } from "@/lib/tokens";

// Limits mirror the CHECK constraints in supabase/migrations/0001_init.sql so that
// the admin sees a friendly message instead of a database error.

const text = (max: number, what: string) =>
  z
    .string()
    .trim()
    .min(1, `${what} can't be empty.`)
    .max(max, `${what} can be at most ${max} characters.`);

const optionalText = (max: number, what: string) =>
  z.string().trim().max(max, `${what} can be at most ${max} characters.`);

const number = (what: string) => z.number(`${what} must be a number.`);

export const eventSchema = z.object({
  name: text(120, "Event name"),
  eventDate: z.union([z.iso.date("Pick a valid date."), z.literal("")]),
});

/** A co-host's email, normalised the way event_cohosts stores it (trimmed, lower case). */
export const cohostEmailSchema = z
  .string()
  .trim()
  .toLowerCase()
  .pipe(z.email("Enter a valid email address.").max(254, "That email is too long."));

export const teamSchema = z.object({
  name: text(60, "Team name"),
  color: z.string().regex(/^#[0-9A-Fa-f]{6}$/, "Pick a colour."),
});

/** Is (max − min) a whole number of steps? Tolerates float error for steps like 0.5. */
const onStep = (min: number, max: number, step: number) => {
  const steps = (max - min) / step;
  return Math.abs(steps - Math.round(steps)) < 1e-9;
};

export const criterionSchema = z
  .object({
    id: idSchema.optional(),
    label: text(60, "Criterion label"),
    description: optionalText(300, "Criterion description"),
    inputType: z.enum(["blocks", "number"]),
    min: number("Min").min(-999999).max(999999),
    max: number("Max").min(-999999).max(999999),
    step: number("Step").positive("Step must be more than 0.").max(999999),
    weight: number("Weight").min(0, "Weight can't be negative.").max(9999),
  })
  .superRefine((criterion, context) => {
    const name = criterion.label || "A criterion";
    if (criterion.max <= criterion.min) {
      context.addIssue({ code: "custom", message: `${name}: max must be more than min.` });
      return;
    }
    if (!onStep(criterion.min, criterion.max, criterion.step)) {
      context.addIssue({
        code: "custom",
        message: `${name}: the step must divide evenly into the range from min to max.`,
      });
      return;
    }
    if (
      criterion.inputType === "blocks" &&
      (criterion.max - criterion.min) / criterion.step > 10
    ) {
      context.addIssue({
        code: "custom",
        message: `${name}: blocks can show at most 11 buttons. Use a number input or a bigger step.`,
      });
    }
  });

export const gameSchema = z.object({
  title: text(120, "Game title"),
  description: optionalText(2000, "Description"),
  scoringMode: z.enum(["judged", "direct"]),
  pointsMode: z.enum(["raw", "placement"]),
  multiplier: number("Multiplier").min(0, "Multiplier can't be negative.").max(9999),
  placementPoints: z
    .array(z.number().int("Placement points must be whole numbers.").min(0).max(100000))
    .min(1, "Add at least one placement value, like 10, 7, 5, 3.")
    .max(30),
  buzzerEnabled: z.boolean(),
  adminNotes: optionalText(4000, "Admin notes"),
  judgeNotes: optionalText(4000, "Judge notes"),
  criteria: z.array(criterionSchema).min(1, "A game needs at least one criterion.").max(20),
});

export const MAX_ITEMS_PER_GAME = 200;

/** A question, sound or video for a game. Media is a link or an uploaded file's path, never both. */
export const itemSchema = z
  .object({
    kind: z.enum(ITEM_KINDS),
    title: optionalText(500, "The text"),
    answer: optionalText(500, "The answer"),
    mediaUrl: z.string().trim().max(2000, "That link is too long."),
    storagePath: z.string().nullable(),
  })
  .superRefine((item, context) => {
    const issue = (message: string) => context.addIssue({ code: "custom", message });
    if (!item.title) {
      return issue(item.kind === "question" ? "Type the question." : "Give it a name, so you can find it in the list.");
    }
    if (item.mediaUrl && item.storagePath) return issue("Use a link or a file, not both.");
    if (item.mediaUrl && !isHttpsUrl(item.mediaUrl)) return issue("The link must start with https://");
    if (item.kind === "question") {
      if (item.mediaUrl && parseYouTube(item.mediaUrl)) {
        issue("A question's picture must be an image, not a YouTube link. Add the video as its own item.");
      }
    } else if (!item.mediaUrl && !item.storagePath) {
      issue(`Paste a link or choose a file for this ${item.kind}.`);
    }
  });

export type ItemDraft = z.input<typeof itemSchema>;
export type CriterionDraft = z.input<typeof criterionSchema>;
export type GameDraft = z.input<typeof gameSchema>;

/** Parses "10, 7, 5, 3" into numbers; invalid parts become NaN so validation reports them. */
export function parsePlacementPoints(value: string): number[] {
  return value
    .split(/[,\s]+/)
    .filter(Boolean)
    .map((part) => Number(part));
}

export function firstError(error: z.ZodError): string {
  return error.issues[0]?.message ?? "Something in the form isn't valid.";
}