package auth

import (
	"encoding/json"
	"fmt"
	"io"
	"math"
	"net/http"
	"strings"
	"unicode/utf8"

	"github.com/gin-gonic/gin"

	"galo/internal/httpx"
)

type Handler struct {
	svc *Service
}

func NewHandler(svc *Service) *Handler { return &Handler{svc: svc} }

type registerRequest struct {
	Email    string `json:"email"`
	Phone    string `json:"phone"`
	Password string `json:"password" binding:"required"`
	Name     string `json:"name" binding:"required"`
}

func (h *Handler) Register(c *gin.Context) {
	var req registerRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_request", "name and password are required"))
		return
	}
	u, pair, err := h.svc.Register(c.Request.Context(), req.Email, req.Phone, req.Password, req.Name)
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusCreated, gin.H{"user": u.Self(), "tokens": pair})
}

type loginRequest struct {
	Identifier string `json:"identifier" binding:"required"`
	Password   string `json:"password" binding:"required"`
}

func (h *Handler) Login(c *gin.Context) {
	var req loginRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_request", "identifier and password are required"))
		return
	}
	u, pair, err := h.svc.Login(c.Request.Context(), req.Identifier, req.Password)
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"user": u.Self(), "tokens": pair})
}

type refreshRequest struct {
	RefreshToken string `json:"refresh_token" binding:"required"`
}

func (h *Handler) Refresh(c *gin.Context) {
	var req refreshRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_request", "refresh_token is required"))
		return
	}
	pair, err := h.svc.Refresh(c.Request.Context(), req.RefreshToken)
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"tokens": pair})
}

func (h *Handler) Logout(c *gin.Context) {
	var req refreshRequest
	_ = c.ShouldBindJSON(&req)
	if req.RefreshToken != "" {
		if err := h.svc.Logout(c.Request.Context(), req.RefreshToken); err != nil {
			httpx.RespondError(c, err)
			return
		}
	}
	c.Status(http.StatusNoContent)
}

func (h *Handler) Me(c *gin.Context) {
	u, err := h.svc.store.GetUserByID(c.Request.Context(), UserID(c))
	if err != nil {
		httpx.RespondError(c, httpx.Unauthorized("unauthorized", "user not found"))
		return
	}
	prefs := u.Preferences
	if prefs == nil {
		prefs = map[string]any{}
	}
	c.JSON(http.StatusOK, gin.H{"user": u.Self(), "preferences": prefs})
}

type updateMeRequest struct {
	Name string `json:"name"`
}

// UpdateMe changes the display name of the authenticated user.
func (h *Handler) UpdateMe(c *gin.Context) {
	var req updateMeRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_request", "name is required"))
		return
	}
	u, err := h.svc.UpdateName(c.Request.Context(), UserID(c), req.Name)
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"user": u.Self()})
}

type changePasswordRequest struct {
	CurrentPassword string `json:"current_password" binding:"required"`
	NewPassword     string `json:"new_password" binding:"required"`
}

// ChangePassword verifies the current password and revokes all refresh tokens.
func (h *Handler) ChangePassword(c *gin.Context) {
	var req changePasswordRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_request", "current_password and new_password are required"))
		return
	}
	if err := h.svc.ChangePassword(c.Request.Context(), UserID(c), req.CurrentPassword, req.NewPassword); err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.Status(http.StatusNoContent)
}

type addIdentifierRequest struct {
	Email string `json:"email"`
	Phone string `json:"phone"`
}

// AddIdentifier adds the one missing login identifier.
func (h *Handler) AddIdentifier(c *gin.Context) {
	var req addIdentifierRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_request", "email or phone is required"))
		return
	}
	u, err := h.svc.AddIdentifier(c.Request.Context(), UserID(c), req.Email, req.Phone)
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"user": u.Self()})
}

type deleteMeRequest struct {
	Password string `json:"password" binding:"required"`
}

// DeleteMe deletes the authenticated account and all cascading content.
func (h *Handler) DeleteMe(c *gin.Context) {
	var req deleteMeRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_request", "password is required"))
		return
	}
	if err := h.svc.DeleteAccount(c.Request.Context(), UserID(c), req.Password); err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.Status(http.StatusNoContent)
}

const (
	maxVisibleAttrs       = 500
	maxLabelEntries       = 500
	maxPreferenceKeyLen   = 128
	maxPreferenceValueLen = 128
	maxCurvePresets       = 100
	maxCurvePresetNameLen = 64
	maxCurvePresetPoints  = 16
)

type photoInfoPreferences struct {
	Visible []string          `json:"visible"`
	Labels  map[string]string `json:"labels,omitempty"`
}

type curvePresetPoint struct {
	X float64 `json:"x"`
	Y float64 `json:"y"`
}

type curvePresetChannels struct {
	RGB   []curvePresetPoint `json:"rgb"`
	Red   []curvePresetPoint `json:"red"`
	Green []curvePresetPoint `json:"green"`
	Blue  []curvePresetPoint `json:"blue"`
}

type curvePreset struct {
	Name     string              `json:"name"`
	Channels curvePresetChannels `json:"channels"`
}

type preferencesPayload struct {
	PhotoInfo    *photoInfoPreferences `json:"photo_info,omitempty"`
	CurvePresets *[]curvePreset        `json:"curve_presets,omitempty"`
}

// normalize trims preset names before they are validated and stored.
func (p *preferencesPayload) normalize() {
	if p.CurvePresets == nil {
		return
	}
	for i := range *p.CurvePresets {
		(*p.CurvePresets)[i].Name = strings.TrimSpace((*p.CurvePresets)[i].Name)
	}
}

func (p preferencesPayload) validate() error {
	pi := p.PhotoInfo
	if pi != nil {
		if len(pi.Visible) > maxVisibleAttrs {
			return fmt.Errorf("too many visible attributes")
		}
		for _, k := range pi.Visible {
			if k == "" || len(k) > maxPreferenceKeyLen {
				return fmt.Errorf("invalid visible attribute key")
			}
		}
		if len(pi.Labels) > maxLabelEntries {
			return fmt.Errorf("too many label overrides")
		}
		for k, v := range pi.Labels {
			if k == "" || len(k) > maxPreferenceKeyLen {
				return fmt.Errorf("invalid label key")
			}
			if len(v) > maxPreferenceValueLen {
				return fmt.Errorf("label value too long")
			}
		}
	}
	if p.CurvePresets != nil {
		return validateCurvePresets(*p.CurvePresets)
	}
	return nil
}

func validateCurvePresets(presets []curvePreset) error {
	if len(presets) > maxCurvePresets {
		return fmt.Errorf("too many curve presets")
	}
	names := make(map[string]struct{}, len(presets))
	for _, preset := range presets {
		if preset.Name == "" || utf8.RuneCountInString(preset.Name) > maxCurvePresetNameLen {
			return fmt.Errorf("invalid curve preset name")
		}
		channels := []struct {
			name   string
			points []curvePresetPoint
		}{
			{"rgb", preset.Channels.RGB},
			{"red", preset.Channels.Red},
			{"green", preset.Channels.Green},
			{"blue", preset.Channels.Blue},
		}
		for _, channel := range channels {
			if len(channel.points) < 2 || len(channel.points) > maxCurvePresetPoints {
				return fmt.Errorf("invalid curve preset points for %s", channel.name)
			}
			for _, pt := range channel.points {
				if math.IsNaN(pt.X) || math.IsNaN(pt.Y) || math.IsInf(pt.X, 0) || math.IsInf(pt.Y, 0) {
					return fmt.Errorf("invalid curve preset point")
				}
				if pt.X < 0 || pt.X > 1 || pt.Y < 0 || pt.Y > 1 {
					return fmt.Errorf("invalid curve preset point")
				}
			}
		}
		if _, dup := names[preset.Name]; dup {
			return fmt.Errorf("duplicate curve preset name")
		}
		names[preset.Name] = struct{}{}
	}
	return nil
}

func (h *Handler) UpdatePreferences(c *gin.Context) {
	body, err := io.ReadAll(io.LimitReader(c.Request.Body, 1<<20))
	if err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_preferences", "could not read request body"))
		return
	}
	var payload preferencesPayload
	if err := json.Unmarshal(body, &payload); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_preferences", "preferences must be a JSON object"))
		return
	}
	payload.normalize()
	if err := payload.validate(); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_preferences", err.Error()))
		return
	}

	ctx := c.Request.Context()
	u, err := h.svc.store.GetUserByID(ctx, UserID(c))
	if err != nil {
		httpx.RespondError(c, httpx.Unauthorized("unauthorized", "user not found"))
		return
	}
	// Merge the submitted sections into the stored blob so saving one section
	// never clears the others. Unknown keys are preserved.
	merged := make(map[string]any, len(u.Preferences)+2)
	for k, v := range u.Preferences {
		merged[k] = v
	}
	if payload.PhotoInfo != nil {
		merged["photo_info"] = payload.PhotoInfo
	}
	if payload.CurvePresets != nil {
		merged["curve_presets"] = *payload.CurvePresets
	}
	if payload.PhotoInfo != nil || payload.CurvePresets != nil {
		raw, err := json.Marshal(merged)
		if err != nil {
			httpx.RespondError(c, httpx.BadRequest("invalid_preferences", "could not encode preferences"))
			return
		}
		if err := h.svc.store.UpdatePreferences(ctx, UserID(c), raw); err != nil {
			httpx.RespondError(c, err)
			return
		}
	}
	c.JSON(http.StatusOK, gin.H{"preferences": merged})
}