// Normalize federation subgraph schemas for graphql-codegen.
//
// Problem: services schema.graphql files are federation subgraphs that use
//   `extend type Query` (with no body) and multiple `extend type Query { ... }`
//   blocks. Standard GraphQL parser used by codegen cannot parse these.
//
// Solution: read all 7 subgraph schema files, merge all `extend type Query`
//   blocks into a single `type Query { ... }`, output to a combined SDL file.
//
// Usage: tsx scripts/normalize-schema.ts
// Output: src/lib/api/__generated__/combined-schema.graphql
//
// Related: spec section 2.4
import * as fs from "node:fs";
import * as path from "node:path";

interface SubgraphSchema {
  name: string;
  content: string;
}

const SCHEMA_FILES = [
  {
    name: "iam",
    path: "../../services/iam/src/graphql/generated/schema.graphql",
  },
  {
    name: "config-service",
    path: "../../services/config-service/src/graphql/generated/schema.graphql",
  },
  {
    name: "core-edu",
    path: "../../services/core-edu/src/graphql/generated/schema.graphql",
  },
  {
    name: "content",
    path: "../../services/content/src/graphql/generated/schema.graphql",
  },
  {
    name: "msg",
    path: "../../services/msg/src/graphql/generated/schema.graphql",
  },
  {
    name: "data-ana",
    path: "../../services/data-ana/src/graphql/generated/schema.graphql",
  },
  {
    name: "ai",
    path: "../../services/ai/src/graphql/generated/schema.graphql",
  },
];

function loadSchemas(): SubgraphSchema[] {
  const baseDir = process.cwd();
  return SCHEMA_FILES.map((f) => ({
    name: f.name,
    content: fs.readFileSync(path.resolve(baseDir, f.path), "utf8"),
  }));
}

// Strip federation `extend type Query` syntax:
// - Remove standalone `extend type Query` (no body)
// - Convert `extend type Query { ... }` blocks to `type Query { ... }`
//   (we collect fields and merge later)
function normalizeSchema(content: string): {
  staticDefs: string;
  queryFields: string[];
} {
  const lines = content.split("\n");
  const staticDefs: string[] = [];
  const queryFields: string[] = [];
  let i = 0;
  while (i < lines.length) {
    const line = lines[i];
    // Match `extend type Query` (no body, single line)
    if (/^\s*extend\s+type\s+Query\s*$/.test(line)) {
      i++;
      continue;
    }
    // Match `extend type Query {` block start
    const blockStart = line.match(/^\s*extend\s+type\s+Query\s*\{/);
    if (blockStart) {
      // Collect fields until matching `}`
      i++;
      while (i < lines.length && !/^\s*\}\s*$/.test(lines[i])) {
        const fieldLine = lines[i];
        if (fieldLine.trim()) {
          queryFields.push(fieldLine);
        }
        i++;
      }
      // Skip closing `}`
      i++;
      continue;
    }
    // Match `type Query {` block (already standard, but merge fields)
    const stdBlockStart = line.match(/^\s*type\s+Query\s*\{/);
    if (stdBlockStart) {
      i++;
      while (i < lines.length && !/^\s*\}\s*$/.test(lines[i])) {
        const fieldLine = lines[i];
        if (fieldLine.trim()) {
          queryFields.push(fieldLine);
        }
        i++;
      }
      i++;
      continue;
    }
    staticDefs.push(line);
    i++;
  }
  return { staticDefs: staticDefs.join("\n"), queryFields };
}

function main(): void {
  const schemas = loadSchemas();
  const allStaticDefs: string[] = [];
  const allQueryFields: string[] = [];

  for (const s of schemas) {
    const { staticDefs, queryFields } = normalizeSchema(s.content);
    allStaticDefs.push(`# === ${s.name} subgraph ===`);
    allStaticDefs.push(staticDefs.trim());
    allQueryFields.push(...queryFields);
  }

  // Deduplicate query fields (in case multiple subgraphs define same field)
  const uniqueQueryFields = Array.from(
    new Set(allQueryFields.map((f) => f.trim())),
  );

  const combined = [
    "# Combined normalized schema for graphql-codegen (federation stripped)",
    "# DO NOT EDIT - generated by scripts/normalize-schema.ts",
    "",
    ...allStaticDefs,
    "",
    "type Query {",
    ...uniqueQueryFields.map((f) => `  ${f}`),
    "}",
    "",
  ].join("\n");

  const outDir = path.resolve(process.cwd(), "src/lib/api/__generated__");
  fs.mkdirSync(outDir, { recursive: true });
  const outPath = path.join(outDir, "combined-schema.graphql");
  fs.writeFileSync(outPath, combined);
  console.log(`Combined schema written to ${outPath}`);
  console.log(`  Query fields: ${uniqueQueryFields.length}`);
}

main();