package sync

import (
	"encoding/json"
	"strings"
	"time"

	"smartrun/backend/internal/classify"
	"smartrun/backend/internal/garmin"
	"smartrun/backend/internal/store"
)

// isRunningActivityType reports whether a Garmin activityType.typeKey
// represents a running activity (running, trail_running, treadmill_running,
// track_running, indoor_running, virtual_run, ...) as opposed to other
// sports (padel, cycling, strength training, ...) that also show up in
// get_activities().
func isRunningActivityType(typeKey string) bool {
	return strings.Contains(strings.ToLower(typeKey), "run")
}

func toActivityRow(a garmin.Activity) store.Activity {
	return store.Activity{
		GarminActivityID:        a.ActivityID,
		EventTypeKey:            a.EventType.TypeKey,
		WorkoutID:               a.WorkoutID,
		StartTimeUTC:            a.StartTimeGMT,
		DurationSeconds:         a.Duration,
		DistanceMeters:          a.Distance,
		AvgHR:                   nonZero(a.AverageHR),
		MaxHR:                   nonZero(a.MaxHR),
		AvgSpeedMps:             nonZero(a.AverageSpeed),
		ElevationGainM:          a.ElevationGain,
		AerobicTrainingEffect:   nonZero(a.AerobicTrainingEffect),
		AnaerobicTrainingEffect: nonZero(a.AnaerobicTrainingEffect),
		VO2MaxValue:             a.VO2MaxValue,
		RawJSON:                 string(a.Raw),
	}
}

// nonZero returns nil for a zero value so store columns stay NULL instead of
// a misleading 0 when Garmin simply didn't report that field.
func nonZero(v float64) *float64 {
	if v == 0 {
		return nil
	}
	return &v
}

// toLapRows converts garmin lap DTOs into store rows, computing each lap's
// HR drift (active laps) or recovery rate (rest laps) from the samples that
// fall within that lap's time window. Lap boundaries are derived from
// cumulative elapsed duration rather than parsing StartTimeGMT, since laps
// are contiguous and this sidesteps timezone parsing entirely.
func toLapRows(laps []garmin.Lap, samples []garmin.Sample, targets []*garmin.WorkoutStep, profile store.Profile) []store.Lap {
	rows := make([]store.Lap, 0, len(laps))
	var elapsedStart float64
	for i, l := range laps {
		elapsedEnd := elapsedStart + l.ElapsedDuration

		var driftPtr, recoveryPtr *float64
		lapSamples := samplesInWindow(samples, elapsedStart, elapsedEnd)
		switch l.IntensityType {
		case "ACTIVE":
			if v, ok := classify.HRDrift(lapSamples); ok {
				driftPtr = &v
			}
		case "REST", "RECOVERY", "COOLDOWN", "WARMUP":
			if v, ok := classify.HRRecovery(lapSamples); ok {
				recoveryPtr = &v
			}
		}

		var paceLow, paceHigh, hrLow, hrHigh *float64
		if i < len(targets) && targets[i] != nil {
			paceLow, paceHigh = targetPaceRange(*targets[i])
			hrLow, hrHigh = targetHRRange(*targets[i], profile)
		}

		rows = append(rows, store.Lap{
			LapIndex:            l.LapIndex,
			AvgSpeedMps:         nonZero(l.AverageSpeed),
			IntensityType:       l.IntensityType,
			HRDriftBpmPerMin:    driftPtr,
			HRRecoveryBpmPerMin: recoveryPtr,
			TargetPaceLowMps:    paceLow,
			TargetPaceHighMps:   paceHigh,
			TargetHRLowBpm:      hrLow,
			TargetHRHighBpm:     hrHigh,
			RawJSON:             string(l.Raw),
		})
		elapsedStart = elapsedEnd
	}
	return rows
}

// alignWorkoutTargets zips an activity's recorded laps against its
// structured workout's flattened steps, returning one *garmin.WorkoutStep
// per lap (nil where unavailable).
//
// Confirmed against a real activity (via Garmin Connect's own workout view)
// that recording sometimes continues one lap past the end of the workout's
// last step -- e.g. a 5-minute prescribed cool-down followed by another
// 6:46 the athlete just kept running, logged as a further lap Garmin never
// defined a target for. That shows up here as exactly one more recorded lap
// than the workout has steps, so that specific case zips the steps that do
// exist and leaves the trailing extra lap unmapped, rather than discarding
// every other lap's real target along with it.
//
// Any other mismatch (extra manual laps, auto-lap-by-distance also firing,
// etc.) can't be trusted at all, so every entry comes back nil rather than
// risk showing a target against the wrong lap.
func alignWorkoutTargets(laps []garmin.Lap, workout garmin.Workout) []*garmin.WorkoutStep {
	steps := workout.FlattenSteps()
	out := make([]*garmin.WorkoutStep, len(laps))

	switch len(laps) - len(steps) {
	case 0, 1:
		for i := range steps {
			s := steps[i]
			out[i] = &s
		}
	}
	return out
}

// targetPaceRange returns the (low, high) m/s bounds of a workout step's
// pace-zone target, or (nil, nil) if it doesn't target pace.
func targetPaceRange(step garmin.WorkoutStep) (*float64, *float64) {
	if step.TargetType.TypeKey != "pace.zone" || step.TargetValueOne == nil || step.TargetValueTwo == nil {
		return nil, nil
	}
	lo, hi := *step.TargetValueOne, *step.TargetValueTwo
	if lo > hi {
		lo, hi = hi, lo
	}
	return &lo, &hi
}

// targetHRRange returns the (low, high) bpm bounds of a workout step's
// heart-rate-zone target, or (nil, nil) if it doesn't target heart rate.
// Steps that target a named zone (ZoneNumber) rather than a custom bpm
// range are resolved via the user's Karvonen profile.
func targetHRRange(step garmin.WorkoutStep, profile store.Profile) (*float64, *float64) {
	if step.TargetType.TypeKey != "heart.rate.zone" {
		return nil, nil
	}
	if step.TargetValueOne != nil && step.TargetValueTwo != nil {
		lo, hi := *step.TargetValueOne, *step.TargetValueTwo
		if lo > hi {
			lo, hi = hi, lo
		}
		return &lo, &hi
	}
	if step.ZoneNumber != nil {
		if lo, hi, ok := karvonenBounds(profile, *step.ZoneNumber); ok {
			return &lo, &hi
		}
	}
	return nil, nil
}

// karvonenBounds resolves a named HR zone (1-5) to bpm bounds using the
// user's max/resting heart rate and the zone's %HRR range, both from
// Profile. ok is false when max/resting heart rate aren't configured, or
// the zone number is out of range.
func karvonenBounds(p store.Profile, zone int) (lowBpm, highBpm float64, ok bool) {
	if p.MaxHeartRate == nil || p.RestingHeartRate == nil {
		return 0, 0, false
	}
	maxHR, restHR := *p.MaxHeartRate, *p.RestingHeartRate

	var minPct, maxPct float64
	switch zone {
	case 1:
		minPct, maxPct = p.HRZone1MinPct, p.HRZone1MaxPct
	case 2:
		minPct, maxPct = p.HRZone2MinPct, p.HRZone2MaxPct
	case 3:
		minPct, maxPct = p.HRZone3MinPct, p.HRZone3MaxPct
	case 4:
		minPct, maxPct = p.HRZone4MinPct, p.HRZone4MaxPct
	case 5:
		minPct, maxPct = p.HRZone5MinPct, p.HRZone5MaxPct
	default:
		return 0, 0, false
	}
	return restHR + (minPct/100)*(maxHR-restHR), restHR + (maxPct/100)*(maxHR-restHR), true
}

func samplesInWindow(samples []garmin.Sample, start, end float64) []classify.SampleInfo {
	var out []classify.SampleInfo
	for _, s := range samples {
		if s.ElapsedSeconds < start || s.ElapsedSeconds >= end {
			continue
		}
		out = append(out, classify.SampleInfo{ElapsedSeconds: s.ElapsedSeconds, HeartRate: s.HeartRate})
	}
	return out
}

func toSampleRows(samples []garmin.Sample) []store.Sample {
	rows := make([]store.Sample, len(samples))
	for i, s := range samples {
		rows[i] = store.Sample{
			ElapsedSeconds: s.ElapsedSeconds,
			TimestampMs:    s.TimestampMS,
			HeartRate:      s.HeartRate,
			SpeedMps:       s.SpeedMps,
			DistanceM:      s.DistanceM,
			ElevationM:     s.ElevationM,
		}
	}
	return rows
}

// buildMetricContext computes the classify.MetricContext for one activity
// from its stored summary and laps, ready to evaluate against workout kind
// rules. maxHR is the user's configured max heart rate, used only to derive
// avg_hr_pct_max (Garmin's activity/lap summaries don't include it directly).
func buildMetricContext(a store.Activity, laps []store.Lap, maxHR float64) classify.MetricContext {
	isRace := 0.0
	if a.EventTypeKey == "race" {
		isRace = 1.0
	}
	ctx := classify.MetricContext{
		"duration_seconds": a.DurationSeconds,
		"distance_meters":  a.DistanceMeters,
		"is_race":          isRace,
	}
	if a.AvgSpeedMps != nil && *a.AvgSpeedMps > 0 {
		ctx["avg_pace_sec_per_km"] = 1000 / *a.AvgSpeedMps
	}
	if a.AvgHR != nil {
		ctx["avg_hr"] = *a.AvgHR
		if maxHR > 0 {
			ctx["avg_hr_pct_max"] = *a.AvgHR / maxHR
		}
	}
	if a.MaxHR != nil {
		ctx["max_hr"] = *a.MaxHR
	}
	if a.ElevationGainM != nil {
		ctx["elevation_gain_m"] = *a.ElevationGainM
	}
	if a.AerobicTrainingEffect != nil {
		ctx["aerobic_training_effect"] = *a.AerobicTrainingEffect
	}
	if a.AnaerobicTrainingEffect != nil {
		ctx["anaerobic_training_effect"] = *a.AnaerobicTrainingEffect
	}
	if a.VO2MaxValue != nil {
		ctx["vo2max_value"] = *a.VO2MaxValue
	}

	lapInfos := make([]classify.LapInfo, len(laps))
	var paces []float64
	var maxDrift, maxRecovery float64
	haveDrift, haveRecovery := false, false
	for i, l := range laps {
		lapInfos[i] = classify.LapInfo{IntensityType: l.IntensityType}
		if l.AvgSpeedMps != nil && *l.AvgSpeedMps > 0 {
			paces = append(paces, 1000 / *l.AvgSpeedMps)
		}
		if l.HRDriftBpmPerMin != nil && (!haveDrift || *l.HRDriftBpmPerMin > maxDrift) {
			maxDrift, haveDrift = *l.HRDriftBpmPerMin, true
		}
		if l.HRRecoveryBpmPerMin != nil && (!haveRecovery || *l.HRRecoveryBpmPerMin > maxRecovery) {
			maxRecovery, haveRecovery = *l.HRRecoveryBpmPerMin, true
		}
	}
	if len(laps) > 0 {
		if classify.DetectIntervalPattern(lapInfos) {
			ctx["lap_interval_pattern"] = 1
		} else {
			ctx["lap_interval_pattern"] = 0
		}
	}
	if len(paces) > 0 {
		ctx["lap_pace_stddev"] = classify.LapPaceStdDev(paces)
	}
	if haveDrift {
		ctx["lap_hr_drift_bpm_per_min"] = maxDrift
	}
	if haveRecovery {
		ctx["lap_hr_recovery_bpm_per_min"] = maxRecovery
	}
	return ctx
}

func loadRuleKinds(kinds []store.WorkoutKind) ([]classify.RuleKind, error) {
	rules := make([]classify.RuleKind, 0, len(kinds))
	for _, k := range kinds {
		var node classify.Node
		if err := json.Unmarshal([]byte(k.RuleJSON), &node); err != nil {
			return nil, err
		}
		rules = append(rules, classify.RuleKind{WorkoutKindID: k.ID, Name: k.Name, Rule: node})
	}
	return rules, nil
}

func dateStr(t time.Time) string { return t.Format("2006-01-02") }