package api

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

	"geniusrun/backend/internal/store"
)

// validateProfile checks the HR zones are ascending and gap-free once they
// start, but deliberately does NOT require zone 1 to start at 0% or zone 5
// to end at 100%: real Karvonen HR training zones (e.g. the seeded defaults,
// 50-60/60-70/70-80/80-90/90-100) don't cover the 0-50% range at all --
// below zone 1 simply isn't a named training zone.
func validateProfile(p store.Profile) error {
	if p.RestingHeartRate != nil && p.MaxHeartRate != nil && *p.RestingHeartRate >= *p.MaxHeartRate {
		return errors.New("resting heart rate must be less than max heart rate")
	}
	zones := [][2]float64{
		{p.HRZone1MinPct, p.HRZone1MaxPct},
		{p.HRZone2MinPct, p.HRZone2MaxPct},
		{p.HRZone3MinPct, p.HRZone3MaxPct},
		{p.HRZone4MinPct, p.HRZone4MaxPct},
		{p.HRZone5MinPct, p.HRZone5MaxPct},
	}
	for i, z := range zones {
		if z[0] >= z[1] {
			return errors.New("each HR zone's min must be less than its max")
		}
		if i > 0 && z[0] != zones[i-1][1] {
			return errors.New("HR zones must be contiguous and non-overlapping")
		}
	}
	return nil
}

func (s *Server) handleGetProfile(w http.ResponseWriter, r *http.Request) {
	p, err := s.DB.GetProfile(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, http.StatusOK, p)
}

func (s *Server) handleUpdateProfile(w http.ResponseWriter, r *http.Request) {
	var p store.Profile
	if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	if err := validateProfile(p); err != nil {
		writeError(w, http.StatusBadRequest, err.Error())
		return
	}

	if err := s.DB.UpdateProfile(r.Context(), p); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	s.Garmin.UpdateCredentials(p.GarminEmail, p.GarminPassword)

	updated, err := s.DB.GetProfile(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, http.StatusOK, updated)
}