package api

import (
	"encoding/json"
	"errors"
	"net/http"
	"time"

	"git.fabledsword.com/bvandeusen/minstrel/internal/apierror"
	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
	"git.fabledsword.com/bvandeusen/minstrel/internal/library"
)

// AcoustID recording-id lookup, admin side (M401 #3922).

// acoustIDUnsettledLimit caps the admin list of tracks a lookup could not
// settle. It is a list to read, not to page through.
const acoustIDUnsettledLimit = 200

// acoustIDSettingsResp never carries the key, only whether one is stored.
type acoustIDSettingsResp struct {
	Enabled   bool    `json:"enabled"`
	MinScore  float32 `json:"min_score"`
	APIKeySet bool    `json:"api_key_set"`
}

func acoustIDSettingsRespOf(s library.AcoustIDSettings) acoustIDSettingsResp {
	return acoustIDSettingsResp{Enabled: s.Enabled, MinScore: s.MinScore, APIKeySet: s.APIKey != ""}
}

type acoustIDStatusResp struct {
	Running    bool       `json:"running"`
	LastPassAt *time.Time `json:"last_pass_at"`
	// Problem is why the last pass stopped short, in words for the card.
	Problem string `json:"problem"`
}

// acoustIDCoverageResp: from_tag + from_acoustid + the tracks with no MBID =
// total. ambiguous, no_match and failed are lookup states of tracks with no
// MBID; pending is what the worker still has to look at.
type acoustIDCoverageResp struct {
	Total        int64 `json:"total"`
	FromTag      int64 `json:"from_tag"`
	FromAcoustID int64 `json:"from_acoustid"`
	Ambiguous    int64 `json:"ambiguous"`
	NoMatch      int64 `json:"no_match"`
	Failed       int64 `json:"failed"`
	Pending      int64 `json:"pending"`
}

type acoustIDResp struct {
	Settings acoustIDSettingsResp `json:"settings"`
	// Ready is whether the worker will call AcoustID at all: switched on
	// and holding a key.
	Ready    bool                 `json:"ready"`
	Status   acoustIDStatusResp   `json:"status"`
	Coverage acoustIDCoverageResp `json:"coverage"`
}

// handleGetAcoustID implements GET /api/admin/library/acoustid: the settings,
// what the worker is doing, and how much of the library has an MBID by source.
func (h *handlers) handleGetAcoustID(w http.ResponseWriter, r *http.Request) {
	row, err := library.AcoustIDCoverage(r.Context(), h.pool)
	if err != nil {
		writeErrWithLog(w, h.logger, "admin: get acoustid coverage", apierror.InternalMsg("lookup failed", err))
		return
	}
	cfg := h.acoustIDLookup.Settings().Get()
	st := h.acoustIDLookup.Status()
	resp := acoustIDResp{
		Settings: acoustIDSettingsRespOf(cfg),
		Ready:    cfg.Ready(),
		Status:   acoustIDStatusResp{Running: st.Running, Problem: st.Problem},
		Coverage: acoustIDCoverageResp{
			Total:        row.Total,
			FromTag:      row.FromTag,
			FromAcoustID: row.FromAcoustid,
			Ambiguous:    row.Ambiguous,
			NoMatch:      row.NoMatch,
			Failed:       row.Failed,
			Pending:      row.Pending,
		},
	}
	if !st.LastPassAt.IsZero() {
		at := st.LastPassAt.UTC()
		resp.Status.LastPassAt = &at
	}
	writeJSON(w, http.StatusOK, resp)
}

// acoustIDSettingsReq is the PUT body. api_key left out keeps the stored key;
// an empty string clears it.
type acoustIDSettingsReq struct {
	Enabled  bool    `json:"enabled"`
	MinScore float32 `json:"min_score"`
	APIKey   *string `json:"api_key"`
}

// handleUpdateAcoustIDSettings implements PUT /api/admin/library/acoustid-settings.
func (h *handlers) handleUpdateAcoustIDSettings(w http.ResponseWriter, r *http.Request) {
	var req acoustIDSettingsReq
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeErr(w, apierror.BadRequest("invalid_body", "malformed JSON"))
		return
	}
	saved, err := h.acoustIDLookup.Settings().Set(r.Context(), library.AcoustIDSettingsUpdate{
		Enabled: req.Enabled, MinScore: req.MinScore, APIKey: req.APIKey,
	})
	if err != nil {
		if errors.Is(err, library.ErrAcoustIDSettingOutOfRange) {
			writeErr(w, apierror.BadRequest("invalid_setting", err.Error()))
			return
		}
		writeErrWithLog(w, h.logger, "admin acoustid settings: update failed", apierror.Internal(err))
		return
	}
	writeJSON(w, http.StatusOK, acoustIDSettingsRespOf(saved))
}

// handleRunAcoustIDLookup implements POST /api/admin/library/acoustid/run:
// start a pass now rather than at the next tick. 409 when the lookup is off
// or has no key, so the card can say so rather than appear to do nothing.
func (h *handlers) handleRunAcoustIDLookup(w http.ResponseWriter, _ *http.Request) {
	if !h.acoustIDLookup.Settings().Get().Ready() {
		writeErr(w, apierror.Conflict("not_ready",
			"Switch the AcoustID lookup on and add an API key first."))
		return
	}
	h.acoustIDLookup.Kick()
	w.WriteHeader(http.StatusAccepted)
}

type acoustIDUnsettledResp struct {
	TrackID    string    `json:"track_id"`
	Title      string    `json:"title"`
	Artist     string    `json:"artist"`
	Album      string    `json:"album"`
	FilePath   string    `json:"file_path"`
	State      string    `json:"state"`
	BestScore  *float32  `json:"best_score"`
	Candidates int32     `json:"candidates"`
	Detail     *string   `json:"detail"`
	LookedUpAt time.Time `json:"looked_up_at"`
}

// handleListUnsettledAcoustID implements GET /api/admin/library/acoustid/unsettled:
// the tracks a lookup could not settle (ambiguous or failed), so they can be
// found and tagged by hand.
func (h *handlers) handleListUnsettledAcoustID(w http.ResponseWriter, r *http.Request) {
	rows, err := dbq.New(h.pool).ListUnsettledAcoustIDLookups(r.Context(), acoustIDUnsettledLimit)
	if err != nil {
		writeErrWithLog(w, h.logger, "admin: list unsettled acoustid lookups", apierror.InternalMsg("lookup failed", err))
		return
	}
	out := make([]acoustIDUnsettledResp, 0, len(rows))
	for _, row := range rows {
		out = append(out, acoustIDUnsettledResp{
			TrackID:    uuidToString(row.ID),
			Title:      row.Title,
			Artist:     row.ArtistName,
			Album:      row.AlbumTitle,
			FilePath:   row.FilePath,
			State:      row.State,
			BestScore:  row.BestScore,
			Candidates: row.Candidates,
			Detail:     row.Detail,
			LookedUpAt: row.LookedUpAt.Time.UTC(),
		})
	}
	writeJSON(w, http.StatusOK, out)
}