import { MigrationInterface, QueryRunner } from "typeorm";

/**
 * Folds each help section's `media[]` array into its markdown body.
 *
 * Attachments used to hang off the section as a separate list, rendered after
 * the text — which meant an author could not put a picture next to the sentence
 * it illustrates, and had two different places to manage media. They are now
 * embedded with markdown's image syntax, and the renderer picks `<img>` or
 * `<video>` from the file extension.
 *
 * Existing entries are converted rather than dropped: an uploaded object
 * becomes `![caption](minio:<key>)`, and a shipped asset path or external URL
 * is kept verbatim. Sections are left alone once they have no `media` key, so
 * re-running does nothing.
 */
interface LegacyMedia {
  src: string;
  caption?: string | null;
}

interface LegacySection {
  id: string;
  heading: string;
  body: string;
  media?: LegacyMedia[];
}

/** Uploaded objects are stored as keys; the `minio:` ref is signed on read. */
function toMarkdown(item: LegacyMedia): string {
  const isStoredObject = !/^(https?:\/\/|\/)/.test(item.src);
  const target = isStoredObject ? `minio:${item.src}` : item.src;
  return `![${item.caption ?? ""}](${target})`;
}

export class SupportHelpInlineMedia3370000000000 implements MigrationInterface {
  name = "SupportHelpInlineMedia3370000000000";

  public async up(queryRunner: QueryRunner): Promise<void> {
    const rows: {
      id: string;
      version: number;
      payload: { sections?: LegacySection[] } & Record<string, unknown>;
    }[] = await queryRunner.query(`
      SELECT id, version, payload
      FROM freight.support_documents
      WHERE slug = 'HELP'
    `);

    for (const row of rows) {
      const sections = row.payload.sections ?? [];
      if (!sections.some((section) => section.media !== undefined)) continue;

      const payload = {
        ...row.payload,
        sections: sections.map(({ media, ...section }) => {
          const embeds = (media ?? []).map(toMarkdown);
          return {
            ...section,
            body: [section.body, ...embeds].filter(Boolean).join("\n\n"),
          };
        }),
      };
      const version = row.version + 1;

      await queryRunner.query(
        `UPDATE freight.support_documents
         SET payload = $1::jsonb, version = $2, updated_at = now()
         WHERE id = $3`,
        [JSON.stringify(payload), version, row.id],
      );

      await queryRunner.query(
        `INSERT INTO freight.support_document_versions
           (document_id, version, payload, actor_id, note)
         VALUES ($1, $2, $3::jsonb, NULL, $4)`,
        [
          row.id,
          version,
          JSON.stringify(payload),
          "Moved attachments inline into the section text",
        ],
      );
    }
  }

  /** Not reversible — see the note on SupportHelpSections3360000000000. */
  public async down(): Promise<void> {
    // no-op
  }
}