package musicbrainz

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"net/url"

	"naviwatcher/internal/normalize"
)

// mbArtistSearchResult models the JSON response of the MusicBrainz artist
// search endpoint (/ws/2/artist?query=artist:<name>&fmt=json). Only the
// fields we need for MBID resolution are decoded.
type mbArtistSearchResult struct {
	Artists []struct {
		ID   string `json:"id"`
		Name string `json:"name"`
		Score int   `json:"score"`
	} `json:"artists"`
}

// minResolutionScore is the minimum MusicBrainz search score (0-100) we accept
// for an MBID resolution. Below this, the best hit is too weak a match to
// trust, and caching it would silently pollute an artist's discography with
// the wrong MusicBrainz data.
const minResolutionScore = 80

// ResolveArtistMBID resolves a MusicBrainz artist ID (MBID) for the given
// artist name by querying the MusicBrainz artist search endpoint. It returns
// the ID of the highest-scoring matching artist, but only when that artist's
// normalized name actually matches the requested name (and its search score is
// at or above minResolutionScore). An error is returned if the search yields
// no usable match, the response cannot be parsed, or the underlying request
// fails. Rejecting a low-confidence hit lets the caller surface the problem
// instead of caching a wrong MBID.
func (c *MusicBrainzClient) ResolveArtistMBID(ctx context.Context, name string) (string, error) {
	params := url.Values{}
	params.Set("query", fmt.Sprintf("artist:%s", name))
	params.Set("fmt", "json")
	path := "/artist?" + params.Encode()

	body, err := c.doGet(ctx, path)
	if err != nil {
		return "", fmt.Errorf("resolve MBID for artist %q: %w", name, err)
	}

	var result mbArtistSearchResult
	if err := json.Unmarshal(body, &result); err != nil {
		return "", fmt.Errorf("parse artist search response for %q: %w", name, err)
	}

	if len(result.Artists) == 0 {
		return "", fmt.Errorf("no MusicBrainz artist found for %q", name)
	}

	best := result.Artists[0]
	if best.Score < minResolutionScore {
		return "", fmt.Errorf("no confident MusicBrainz match for %q (best candidate %q scored %d, need >= %d)", name, best.Name, best.Score, minResolutionScore)
	}
	// Even with a high score, require the normalized name to match, guarding
	// against score inflation on name collisions (e.g. tribute acts).
	if normalize.NormalizeArtistName(best.Name) != normalize.NormalizeArtistName(name) {
		log.Printf("MusicBrainz MBID resolution skipped for %q: best candidate %q did not match by name", name, best.Name)
		return "", fmt.Errorf("best MusicBrainz candidate %q does not match %q by name", best.Name, name)
	}

	return best.ID, nil
}