import type {
  BuiltSection,
  RenderContext,
  RuntimeIssue,
  SectionBuilder,
} from './runtime-contracts';
import { SECTION_ORDER } from './runtime-contracts';

export interface SectionComposerResult {
  sections: BuiltSection[];
  issues: RuntimeIssue[];
}

export async function composeSections(
  context: RenderContext,
  builders: SectionBuilder[],
): Promise<SectionComposerResult> {
  const builderByRole = new Map(builders.map((builder) => [builder.role, builder]));
  const sections: BuiltSection[] = [];
  const issues: RuntimeIssue[] = [];

  for (const role of SECTION_ORDER) {
    const policy = context.policyBySection.get(role);
    if (!policy?.enabled) {
      continue;
    }

    const builder = builderByRole.get(role);
    if (!builder) {
      issues.push({
        code: 'INVALID_TEMPLATE',
        severity: policy.required ? 'error' : 'warning',
        message: 'No section builder is registered for an enabled section.',
        details: { role },
      });
      continue;
    }

    const section = await builder.build(context);
    sections.push(section);
    issues.push(...section.issues);
  }

  return { sections, issues };
}