const TMDB_BASE = "https://api.themoviedb.org/3";
const LANGUAGE = "en-US";

export interface TmdbSearchResult {
  id: number;
  title: string;
  release_date: string;
  poster_path: string | null;
  overview: string;
}

export interface TmdbMovieDetails {
  id: number;
  title: string;
  release_date: string;
  runtime: number | null;
  overview: string;
  poster_path: string | null;
  backdrop_path: string | null;
  genres: Array<{ id: number; name: string }>;
  budget: number;
  revenue: number;
  production_countries: Array<{ iso_3166_1: string; name: string }>;
  production_companies: Array<{ name: string }>;
  spoken_languages: Array<{ english_name: string }>;
  release_dates?: {
    results: Array<{
      iso_3166_1: string;
      release_dates: Array<{
        certification: string;
        type: number;
        note: string;
      }>;
    }>;
  };
  keywords?: {
    keywords: Array<{ id: number; name: string }>;
  };
  credits?: {
    cast: Array<{ name: string; character: string }>;
    crew: Array<{ name: string; job: string; department: string }>;
  };
}

function getApiKey(): string {
  const key = process.env.TMDB_API_KEY;
  if (!key) {
    throw new Error("TMDB_API_KEY is not set");
  }
  return key;
}

async function tmdbFetch<T>(path: string, params: Record<string, string> = {}) {
  const url = new URL(`${TMDB_BASE}${path}`);
  url.searchParams.set("api_key", getApiKey());
  url.searchParams.set("language", LANGUAGE);

  for (const [key, value] of Object.entries(params)) {
    url.searchParams.set(key, value);
  }

  const response = await fetch(url.toString(), {
    next: { revalidate: 3600 },
  });

  if (!response.ok) {
    throw new Error(`TMDB request failed: ${response.status}`);
  }

  return response.json() as Promise<T>;
}

export async function searchMovies(query: string): Promise<TmdbSearchResult[]> {
  if (!query.trim()) {
    return [];
  }

  const data = await tmdbFetch<{ results: TmdbSearchResult[] }>("/search/movie", {
    query: query.trim(),
    include_adult: "false",
  });

  return data.results.slice(0, 8);
}

export async function getMovieDetails(movieId: number): Promise<TmdbMovieDetails> {
  return tmdbFetch<TmdbMovieDetails>(`/movie/${movieId}`, {
    append_to_response: "release_dates,credits,keywords",
  });
}

export function getPosterUrl(path: string | null, size: "w185" | "w500" | "original" = "w500") {
  if (!path) {
    return null;
  }
  return `https://image.tmdb.org/t/p/${size}${path}`;
}

export function getUsCertification(movie: TmdbMovieDetails): string | null {
  const us = movie.release_dates?.results.find((r) => r.iso_3166_1 === "US");
  if (!us) {
    return null;
  }

  const theatrical = us.release_dates.find((r) => r.type === 3 && r.certification);
  if (theatrical?.certification) {
    return theatrical.certification;
  }

  const any = us.release_dates.find((r) => r.certification);
  return any?.certification ?? null;
}

export function formatMovieContext(movie: TmdbMovieDetails): string {
  const genres = movie.genres.map((g) => g.name).join(", ");
  const keywords = movie.keywords?.keywords.map((k) => k.name).join(", ") ?? "";
  const certification = getUsCertification(movie);
  const directors = movie.credits?.crew
    .filter((c) => c.job === "Director")
    .map((c) => c.name)
    .join(", ");
  const leadCast = movie.credits?.cast
    .slice(0, 5)
    .map((c) => `${c.name} as ${c.character}`)
    .join("; ");

  const releaseDates = movie.release_dates?.results
    .map((country) => {
      const certs = country.release_dates
        .filter((r) => r.certification)
        .map((r) => r.certification);
      const unique = [...new Set(certs)];
      if (unique.length === 0) {
        return null;
      }
      return `${country.iso_3166_1}: ${unique.join(", ")}`;
    })
    .filter(Boolean)
    .join("\n");

  return [
    `Title: ${movie.title}`,
    `Year: ${movie.release_date?.slice(0, 4) ?? "Unknown"}`,
    `Runtime: ${movie.runtime ?? "Unknown"} minutes`,
    `Genres: ${genres}`,
    `Overview: ${movie.overview}`,
    certification ? `US Certification: ${certification}` : null,
    keywords ? `Keywords: ${keywords}` : null,
    directors ? `Director(s): ${directors}` : null,
    leadCast ? `Lead cast: ${leadCast}` : null,
    movie.budget ? `Budget: $${movie.budget.toLocaleString("en-US")}` : null,
    movie.revenue ? `Revenue: $${movie.revenue.toLocaleString("en-US")}` : null,
    releaseDates ? `International certifications:\n${releaseDates}` : null,
  ]
    .filter(Boolean)
    .join("\n");
}