package api

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

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

// fingerprintSettingsBody is the wire shape for GET and PUT
// /api/admin/library/fingerprint-settings (M400 #3913). The threshold travels as
// the bit-error rate the matcher uses; the card presents it as a match percentage.
type fingerprintSettingsBody struct {
	Enabled                 bool    `json:"enabled"`
	ChromaprintLengthSec    int32   `json:"chromaprint_length_sec"`
	AcousticMaxBitErrorRate float64 `json:"acoustic_max_bit_error_rate"`
	BackfillConcurrency     int32   `json:"backfill_concurrency"`
	SweepIntervalHours      int32   `json:"sweep_interval_hours"`
	// AutoResolve is a pointer so a client that predates it (M498) and leaves
	// it out keeps the saved value rather than switching the resolver off.
	AutoResolve *bool `json:"auto_resolve"`
}

func fingerprintSettingsBodyOf(s library.FingerprintSettings) fingerprintSettingsBody {
	return fingerprintSettingsBody{
		Enabled:                 s.Enabled,
		ChromaprintLengthSec:    s.ChromaprintLengthSec,
		AcousticMaxBitErrorRate: s.AcousticMaxBitErrorRate,
		BackfillConcurrency:     s.BackfillConcurrency,
		SweepIntervalHours:      s.SweepIntervalHours,
		AutoResolve:             &s.AutoResolve,
	}
}

// handleGetFingerprintSettings implements GET /api/admin/library/fingerprint-settings.
func (h *handlers) handleGetFingerprintSettings(w http.ResponseWriter, _ *http.Request) {
	writeJSON(w, http.StatusOK, fingerprintSettingsBodyOf(h.fingerprintSettings.Get()))
}

// handleUpdateFingerprintSettings implements PUT /api/admin/library/fingerprint-settings.
//
// A whole-row write. A body that leaves a field out decodes it as zero, which no
// field accepts, so a partial save is refused rather than zeroing what it omitted.
// auto_resolve is the exception: left out, it keeps its saved value.
// The saved settings reach the scanner and both workers at once: they share the
// service instance.
func (h *handlers) handleUpdateFingerprintSettings(w http.ResponseWriter, r *http.Request) {
	var req fingerprintSettingsBody
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeErr(w, apierror.BadRequest("invalid_body", "malformed JSON"))
		return
	}
	autoResolve := h.fingerprintSettings.Get().AutoResolve
	if req.AutoResolve != nil {
		autoResolve = *req.AutoResolve
	}
	saved, err := h.fingerprintSettings.Set(r.Context(), library.FingerprintSettings{
		Enabled:                 req.Enabled,
		ChromaprintLengthSec:    req.ChromaprintLengthSec,
		AcousticMaxBitErrorRate: req.AcousticMaxBitErrorRate,
		BackfillConcurrency:     req.BackfillConcurrency,
		SweepIntervalHours:      req.SweepIntervalHours,
		AutoResolve:             autoResolve,
	})
	if err != nil {
		// Validation mirrors migration 0061's CHECKs and names the field.
		if errors.Is(err, library.ErrFingerprintSettingOutOfRange) {
			writeErr(w, apierror.BadRequest("invalid_setting", err.Error()))
			return
		}
		writeErrWithLog(w, h.logger, "admin fingerprint settings: update failed", apierror.Internal(err))
		return
	}
	writeJSON(w, http.StatusOK, fingerprintSettingsBodyOf(saved))
}