import type {
	SectionConventionSets,
} from "../config";
import { resolveSectionConventions } from "../config";
import type { SectionMeta, TransformResult } from "../types";

/**
 * Adds section convention exports (sync, eager, layout, cache)
 * to section files based on metadata extracted during analysis.
 *
 * These exports are read by generate-sections.ts in @decocms/blocks-cli
 * to build the sections.gen.ts registry.
 *
 * The set of section *names* that get hints applied is configurable
 * via `.deco-migrate.config.json` (see `migrate/config.ts`). The exported
 * `transformSectionConventions` keeps a back-compat signature using the
 * baked-in defaults; new callers should prefer
 * `createSectionConventionsTransform(sets)` so config can drive the lists.
 */

function getSectionBasename(filePath: string): string {
	return filePath.split("/").pop()?.replace(/\.\w+$/, "") || "";
}

/**
 * Build a `transformSectionConventions` closure bound to the given
 * resolved sets. This is the preferred entry point — the caller (usually
 * `phase-transform`) loads config once and passes the sets in.
 */
export function createSectionConventionsTransform(
	sets: SectionConventionSets,
) {
	return (
		content: string,
		sectionMeta: SectionMeta | undefined,
	): TransformResult => transformWithSets(content, sectionMeta, sets);
}

/** Default-configured transform. Uses the baked-in defaults from `config.ts`. */
const defaultSets = resolveSectionConventions(null);

export function transformSectionConventions(
	content: string,
	sectionMeta: SectionMeta | undefined,
): TransformResult {
	return transformWithSets(content, sectionMeta, defaultSets);
}

function transformWithSets(
	content: string,
	sectionMeta: SectionMeta | undefined,
	sets: SectionConventionSets,
): TransformResult {
	if (!sectionMeta) {
		return { content, changed: false, notes: [] };
	}

	const notes: string[] = [];
	let result = content;
	let changed = false;
	const basename = getSectionBasename(sectionMeta.path);

	// Header, footer, theme → eager + sync + layout
	if (sectionMeta.isHeader || sectionMeta.isFooter || sectionMeta.isTheme) {
		if (!result.includes("export const eager")) {
			result += "\nexport const eager = true;\n";
			notes.push("Added: export const eager = true");
			changed = true;
		}
		if (!result.includes("export const sync")) {
			result += "export const sync = true;\n";
			notes.push("Added: export const sync = true");
			changed = true;
		}
		// Header in golden does NOT have layout=true; only footer+theme do
		if (
			(sectionMeta.isFooter || sectionMeta.isTheme) &&
			!result.includes("export const layout")
		) {
			result += "export const layout = true;\n";
			notes.push("Added: export const layout = true");
			changed = true;
		}
	}

	// Known eager+sync sections (non-layout)
	if (sets.eagerSync.has(basename)) {
		if (!result.includes("export const eager")) {
			result += "\nexport const eager = true;\n";
			notes.push(`Added: export const eager = true (${basename})`);
			changed = true;
		}
		if (!result.includes("export const sync")) {
			result += "export const sync = true;\n";
			notes.push(`Added: export const sync = true (${basename})`);
			changed = true;
		}
	}

	// Known sync-only sections
	if (sets.sync.has(basename) && !result.includes("export const sync")) {
		result += "\nexport const sync = true;\n";
		notes.push(`Added: export const sync = true (${basename})`);
		changed = true;
	}

	// Listing cache sections
	if (
		sets.listingCache.has(basename) &&
		!result.includes("export const cache")
	) {
		result += '\nexport const cache = "listing";\n';
		notes.push(`Added: export const cache = "listing" (${basename})`);
		changed = true;
	}

	// Static cache sections
	if (
		sets.staticCache.has(basename) &&
		!result.includes("export const cache")
	) {
		result += '\nexport const cache = "static";\n';
		notes.push(`Added: export const cache = "static" (${basename})`);
		changed = true;
	}

	// Generic: listing sections not already matched above
	if (sectionMeta.isListing && !result.includes("export const cache")) {
		result += '\nexport const cache = "listing";\n';
		notes.push('Added: export const cache = "listing"');
		changed = true;
	}

	// Sections with loaders that use device → add sync (needs SSR device detection)
	if (
		sectionMeta.hasLoader &&
		sectionMeta.loaderUsesDevice &&
		!result.includes("export const sync")
	) {
		result += "\nexport const sync = true;\n";
		notes.push("Added: export const sync = true (loader uses device)");
		changed = true;
	}

	// Sections that render nested Section children need sync so they're in
	// the syncComponents registry (SectionRenderer resolves the string key).
	const hasNestedSections =
		/children:\s*Section\b/.test(result) ||
		/fallback:\s*Section\b/.test(result);
	if (hasNestedSections && !result.includes("export const sync")) {
		result += "\nexport const sync = true;\n";
		notes.push(
			"Added: export const sync = true (renders nested Section children)",
		);
		changed = true;
	}

	// Re-export sections that wrap PDP/nested content need sync too.
	// Detect: file is a re-export AND the target component renders nested Sections
	const isReExport = /^export\s+\{[^}]*default[^}]*\}\s+from\s+/.test(
		result.trim(),
	);
	if (
		isReExport &&
		(basename === "MountedPDP" || basename === "NotFoundChallenge")
	) {
		if (!result.includes("export const sync")) {
			result += "\nexport const sync = true;\n";
			notes.push(`Added: export const sync = true (re-export: ${basename})`);
			changed = true;
		}
	}

	// Don't add LoadingFallback re-exports to thin section files —
	// we can't guarantee the target component exports it.
	// Instead, if it's a listing section, a generic skeleton will be added below.

	// Generate a basic LoadingFallback if the section doesn't have one
	// and it's a listing section (visible skeleton improvement)
	if (
		sectionMeta.isListing &&
		!sectionMeta.hasLoadingFallback &&
		!result.includes("LoadingFallback")
	) {
		result += `
export function LoadingFallback() {
  return (
    <div className="w-full py-8">
      <div className="container mx-auto px-4">
        <div className="h-6 w-48 bg-base-200 animate-pulse rounded mb-4" />
        <div className="grid grid-cols-2 md:grid-cols-4 gap-4">
          {Array.from({ length: 4 }).map((_, i) => (
            <div key={i} className="flex flex-col gap-2">
              <div className="aspect-square bg-base-200 animate-pulse rounded" />
              <div className="h-4 bg-base-200 animate-pulse rounded w-3/4" />
              <div className="h-4 bg-base-200 animate-pulse rounded w-1/2" />
            </div>
          ))}
        </div>
      </div>
    </div>
  );
}
`;
		notes.push("Added: LoadingFallback skeleton for listing section");
		changed = true;
	}

	return { content: result, changed, notes };
}