package api

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

	"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
}

// profilePayload is the profile API's request/response shape: the profiles
// row plus Name, which lives on the users row (the account's single
// human-facing name) but is edited from the same Profile screen.
type profilePayload struct {
	store.Profile
	Name string
}

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

func (s *Server) handleUpdateProfile(w http.ResponseWriter, r *http.Request) {
	userID := userIDFromContext(r.Context())
	var p profilePayload
	if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	if strings.TrimSpace(p.Name) == "" {
		writeError(w, http.StatusBadRequest, "name is required")
		return
	}
	if err := validateProfile(p.Profile); err != nil {
		writeError(w, http.StatusBadRequest, err.Error())
		return
	}

	if err := s.DB.UpdateProfile(r.Context(), userID, p.Profile); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if err := s.DB.UpdateUserName(r.Context(), userID, strings.TrimSpace(p.Name)); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	client, err := s.clientFor(r.Context(), userID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	client.UpdateCredentials(p.GarminEmail, p.GarminPassword)

	updated, err := s.DB.GetProfile(r.Context(), userID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSON(w, http.StatusOK, profilePayload{Profile: updated, Name: strings.TrimSpace(p.Name)})
}

// handleDeleteProfile permanently deletes the signed-in user's entire
// geniusrun account (profile, workout kinds/paces, activities and
// everything under them, sync state/runs -- see schema.sql's ON DELETE
// CASCADE from users(id)) and tears down their cached Garmin client and
// token-store directory. It does not touch the session cookie itself --
// the frontend follows a successful call with a real logout navigation
// (see docs/superpowers/specs/2026-07-26-profile-deletion-design.md).
func (s *Server) handleDeleteProfile(w http.ResponseWriter, r *http.Request) {
	userID := userIDFromContext(r.Context())

	s.mu.Lock()
	inProgress := s.userSyncRunning[userID]
	s.mu.Unlock()
	if inProgress {
		writeError(w, http.StatusConflict, "a sync is in progress for this account; wait for it to finish before deleting your profile")
		return
	}

	if err := s.DB.DeleteUser(r.Context(), userID); err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	s.removeUserClient(userID)
	w.WriteHeader(http.StatusNoContent)
}