// What the autoconfiguration module (automx2) holds, as stored: its provider, server, domain and server_domain
// rows, read from its SQLite file inside its container with the sqlite3 program the image carries, opened
// read-only. Nothing is written and nothing is interpreted: the rows are the evidence for what automx answers
// to mail clients (novox/hq issue 1630, ADR 0480), and the reason the answer may be empty.

import type { Exec } from "./health.js";

export const AUTOMX_DATABASE = "/data/db.sqlite";

/** The tables read, each with the one query that reads it. Fixed text: the tool takes no query from its caller. */
export const AUTOMX_TABLES: Record<string, string> = {
  provider: "SELECT id, name, short_name FROM provider ORDER BY id",
  server: "SELECT id, prio, name, port, type, socket_type, user_name, authentication FROM server ORDER BY id",
  domain: "SELECT id, name, provider_id, ldapserver_id FROM domain ORDER BY id",
  server_domain: "SELECT server_id, domain_id FROM server_domain ORDER BY domain_id, server_id",
};

export type Row = Record<string, string | number | null>;

export type AutomxRows = {
  database: string;
  tables: Record<string, Row[]>;
  /** servers whose name is empty: the client is told an empty host name for them */
  empty_names: { id: number; type: string }[];
  /** tables that could not be read, each with what sqlite3 or docker said on one line */
  unreadable: Record<string, string>;
};

/** sqlite3 -json prints one JSON array, or nothing at all for a table without rows. */
export function parseRows(output: string): Row[] {
  const text = output.trim();
  if (text === "") return [];
  const rows = JSON.parse(text) as unknown;
  if (!Array.isArray(rows)) throw new Error("sqlite3 did not print a list of rows");
  return rows as Row[];
}

/** The command that reads one table: read-only, JSON, one fixed statement. */
export function readCommand(sql: string): string[] {
  return ["sqlite3", "-readonly", "-json", AUTOMX_DATABASE, sql];
}

/** Read every table; one that fails is said in `unreadable` and does not hide the others. */
export async function readAutomx(exec: Exec, container: string): Promise<AutomxRows> {
  const answer: AutomxRows = { database: AUTOMX_DATABASE, tables: {}, empty_names: [], unreadable: {} };
  for (const [table, sql] of Object.entries(AUTOMX_TABLES)) {
    try {
      answer.tables[table] = parseRows(await exec(container, readCommand(sql)));
    } catch (e) {
      const err = e as { stderr?: string; message?: string };
      const text = (err?.stderr ?? "").trim() || (err?.message ?? String(e)).trim();
      answer.unreadable[table] = text.split("\n").map((l) => l.trim()).filter(Boolean)[0] ?? "it failed and said nothing";
    }
  }
  for (const s of answer.tables.server ?? []) {
    if (String(s.name ?? "").trim() === "") answer.empty_names.push({ id: Number(s.id), type: String(s.type) });
  }
  return answer;
}