package auth

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"

	"github.com/gin-gonic/gin"

	"shared-album/internal/httpx"
)

type Handler struct {
	svc *Service
}

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

type registerRequest struct {
	Email    string `json:"email" binding:"required"`
	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", "email, password and name are required"))
		return
	}
	u, pair, err := h.svc.Register(c.Request.Context(), req.Email, req.Password, req.Name)
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusCreated, gin.H{"user": u.Public(), "tokens": pair})
}

type loginRequest struct {
	Email    string `json:"email" 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", "email and password are required"))
		return
	}
	u, pair, err := h.svc.Login(c.Request.Context(), req.Email, req.Password)
	if err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"user": u.Public(), "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.Public(), "preferences": prefs})
}

const (
	maxVisibleAttrs       = 500
	maxLabelEntries       = 500
	maxPreferenceKeyLen   = 128
	maxPreferenceValueLen = 128
)

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

type preferencesPayload struct {
	PhotoInfo *photoInfoPreferences `json:"photo_info,omitempty"`
}

func (p preferencesPayload) validate() error {
	pi := p.PhotoInfo
	if pi == nil {
		return 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")
		}
	}
	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
	}
	if err := payload.validate(); err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_preferences", err.Error()))
		return
	}
	raw, err := json.Marshal(payload)
	if err != nil {
		httpx.RespondError(c, httpx.BadRequest("invalid_preferences", "could not encode preferences"))
		return
	}
	if err := h.svc.store.UpdatePreferences(c.Request.Context(), UserID(c), raw); err != nil {
		httpx.RespondError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"preferences": payload})
}