import type { MetadataRoute } from 'next';
import {
    getBuildingsForMod,
    getMods,
    getUnitsForMod,
    SITE_URL,
} from '@/lib/api-server';

export const dynamic = 'force-dynamic';

export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
    const mods = (await getMods()) ?? [];

    const modEntries: MetadataRoute.Sitemap = mods.map((mod) => ({
        url: `${SITE_URL}/mod/${mod.id}`,
        lastModified: new Date(),
        changeFrequency: 'weekly',
        priority: 0.8,
    }));

    const entries: MetadataRoute.Sitemap = [...modEntries];

    // Gather races/units/buildings per mod (limit parallelism)
    const details = await Promise.all(
        mods.slice(0, 20).map(async (mod) => {
            const [units, buildings] = await Promise.all([
                getUnitsForMod(mod.id),
                getBuildingsForMod(mod.id),
            ]);
            return { mod, units, buildings };
        })
    );

    for (const { mod, units, buildings } of details) {
        const raceIds = new Set<string>();
        for (const unitGroup of units ?? []) raceIds.add(unitGroup.race.id);
        for (const buildingGroup of buildings ?? []) raceIds.add(buildingGroup.race.id);

        for (const raceId of raceIds) {
            entries.push({
                url: `${SITE_URL}/mod/${mod.id}/race/${raceId}`,
                lastModified: new Date(),
                changeFrequency: 'weekly',
                priority: 0.7,
            });
        }
        for (const unitGroup of units ?? []) {
            for (const unit of [...unitGroup.infantry, ...unitGroup.support, ...unitGroup.tech]) {
                entries.push({
                    url: `${SITE_URL}/mod/${mod.id}/race/${unitGroup.race.id}/unit/${unit.id}`,
                    lastModified: new Date(),
                    changeFrequency: 'monthly',
                    priority: 0.5,
                });
            }
        }
        for (const buildingGroup of buildings ?? []) {
            for (const building of [...buildingGroup.buildings, ...buildingGroup.buildingsAdvanced]) {
                entries.push({
                    url: `${SITE_URL}/mod/${mod.id}/race/${buildingGroup.race.id}/building/${building.id}`,
                    lastModified: new Date(),
                    changeFrequency: 'monthly',
                    priority: 0.5,
                });
            }
        }
    }

    return [
        {
            url: SITE_URL,
            lastModified: new Date(),
            changeFrequency: 'daily',
            priority: 1,
        },
        ...entries,
    ];
}