import { z } from "zod";

const MAX_OPTIONS = 50;
const text = z.string().max(2000);

const options = z.array(z.union([z.string().max(200), z.object({ label: z.string().max(200) })])).max(MAX_OPTIONS);

const fieldSchema = z.discriminatedUnion("type", [
  z.object({ type: z.literal("markdown"), attributes: z.object({ value: z.string().max(10000) }) }),
  z.object({
    type: z.enum(["input", "textarea"]),
    id: z.string().max(100).optional(),
    attributes: z.object({
      label: text,
      description: text.optional(),
      placeholder: text.optional(),
      value: z.string().max(10000).optional(),
      render: z.string().max(50).optional(),
    }),
    validations: z.object({ required: z.boolean().optional() }).optional(),
  }),
  z.object({
    type: z.literal("dropdown"),
    id: z.string().max(100).optional(),
    attributes: z.object({
      label: text,
      description: text.optional(),
      multiple: z.boolean().optional(),
      options,
    }),
    validations: z.object({ required: z.boolean().optional() }).optional(),
  }),
  z.object({
    type: z.literal("checkboxes"),
    id: z.string().max(100).optional(),
    attributes: z.object({ label: text, description: text.optional(), options }),
  }),
]);

const labels = z
  .union([z.array(z.string().max(50)).max(20), z.string().max(500)])
  .optional()
  .transform((value) =>
    (typeof value === "string" ? value.split(",") : (value ?? [])).map((label) => label.trim()).filter(Boolean),
  );

/** `.gitfor/ISSUE_TEMPLATE/*.yml` issue form, validated with the same shape as GitHub issue forms. */
export const issueFormSchema = z.object({
  name: z.string().max(200),
  description: z.string().max(500).default(""),
  title: z.string().max(256).default(""),
  labels,
  body: z.array(fieldSchema).max(50),
});

/** Front matter of a markdown issue template. */
export const markdownTemplateSchema = z.object({
  name: z.string().max(200),
  about: z.string().max(500).default(""),
  title: z.string().max(256).default(""),
  labels,
});

export const templateConfigSchema = z.object({
  blank_issues_enabled: z.boolean().default(true),
  contact_links: z
    .array(
      z.object({
        name: z.string().max(200),
        url: z
          .url()
          .max(1000)
          .refine((value) => /^https?:\/\//i.test(value), "Contact links must use http or https"),
        about: z.string().max(500).default(""),
      }),
    )
    .max(20)
    .default([]),
});

export type IssueFormField = z.infer<typeof fieldSchema>;

export type IssueTemplate = {
  file: string;
  name: string;
  about: string;
  title: string;
  labels: string[];
} & ({ kind: "markdown"; body: string } | { kind: "form"; fields: IssueFormField[] });

export type TemplateConfig = z.infer<typeof templateConfigSchema>;

export function optionLabel(option: string | { label: string }): string {
  return typeof option === "string" ? option : option.label;
}

/** Renders submitted form answers into the issue body the way GitHub issue forms do. */
export function renderFormBody(fields: IssueFormField[], answers: Record<string, string | string[]>): string {
  const sections: string[] = [];
  fields.forEach((field, index) => {
    if (field.type === "markdown") return;
    const key = field.id ?? `field-${index}`;
    const answer = answers[key];
    if (field.type === "checkboxes") {
      const checked = new Set(Array.isArray(answer) ? answer : []);
      const lines = field.attributes.options.map((option) => {
        const label = optionLabel(option);
        return `- [${checked.has(label) ? "X" : " "}] ${label}`;
      });
      sections.push(`### ${field.attributes.label}\n\n${lines.join("\n")}`);
      return;
    }
    const value = Array.isArray(answer) ? answer.join(", ") : (answer ?? "").trim();
    const rendered =
      field.type === "textarea" && field.attributes.render && value
        ? `\`\`\`${field.attributes.render}\n${value}\n\`\`\``
        : value || "_No response_";
    sections.push(`### ${field.attributes.label}\n\n${rendered}`);
  });
  return sections.join("\n\n");
}