package handler

import (
	"errors"
	"net/http"

	"git.yuntuo.hk/k2safe/go-omni"
	"git.yuntuo.hk/k2safe/go-omni/examples/reference/model"
	"git.yuntuo.hk/k2safe/go-omni/examples/reference/service"
)

type Users struct {
	service *service.Users
}

func NewUsers(service *service.Users) *Users {
	return &Users{service: service}
}

func (h *Users) RegisterRoutes(api *omni.RouterGroup, writeMiddleware, deleteMiddleware omni.Middleware) {
	users := api.Group("/users")
	users.POST("", h.Create, writeMiddleware)
	users.GET("", h.List)
	users.GET("/:id", h.Get)
	users.PUT("/:id", h.Update, writeMiddleware)
	users.DELETE("/:id", h.Delete, writeMiddleware, deleteMiddleware)
}

// HTTP-specific validation tags stay here, outside the business model.
type userBody struct {
	Name  string `json:"name" binding:"required,max=100"`
	Email string `json:"email" binding:"required,email,max=254"`
}

type userPath struct {
	ID int64 `uri:"id" binding:"gt=0"`
}

type listQuery struct {
	Page     int `form:"page,default=1" binding:"gte=1"`
	PageSize int `form:"pageSize,default=20" binding:"gte=1,lte=100"`
}

func (h *Users) Create(ctx *omni.Context) error {
	var body userBody
	if err := ctx.BindJSON(&body); err != nil {
		return err
	}
	user, err := h.service.Create(ctx.Request().Context(), model.UserInput(body))
	if err != nil {
		return userError(err)
	}
	return ctx.Created(user)
}

func (h *Users) Get(ctx *omni.Context) error {
	var path userPath
	if err := ctx.BindURI(&path); err != nil {
		return err
	}
	user, err := h.service.Get(ctx.Request().Context(), path.ID)
	if err != nil {
		return userError(err)
	}
	return ctx.OK(user)
}

func (h *Users) List(ctx *omni.Context) error {
	var query listQuery
	if err := ctx.BindQuery(&query); err != nil {
		return err
	}
	page, err := h.service.List(ctx.Request().Context(), query.Page, query.PageSize)
	if err != nil {
		return userError(err)
	}
	return ctx.OK(page)
}

func (h *Users) Update(ctx *omni.Context) error {
	var path userPath
	if err := ctx.BindURI(&path); err != nil {
		return err
	}
	var body userBody
	if err := ctx.BindJSON(&body); err != nil {
		return err
	}
	user, err := h.service.Update(ctx.Request().Context(), path.ID, model.UserInput(body))
	if err != nil {
		return userError(err)
	}
	return ctx.OK(user)
}

func (h *Users) Delete(ctx *omni.Context) error {
	var path userPath
	if err := ctx.BindURI(&path); err != nil {
		return err
	}
	if err := h.service.Delete(ctx.Request().Context(), path.ID); err != nil {
		return userError(err)
	}
	return ctx.NoContent()
}

func userError(err error) error {
	switch {
	case errors.Is(err, model.ErrUserNotFound):
		return omni.NotFound("USER_NOT_FOUND", "user was not found").WithCause(err)
	case errors.Is(err, model.ErrEmailTaken):
		return omni.NewError(http.StatusConflict, "EMAIL_TAKEN", "email is already in use").WithCause(err)
	case errors.Is(err, model.ErrInvalidUser):
		return omni.BadRequest("INVALID_USER", "name or email is invalid").WithCause(err)
	case errors.Is(err, model.ErrInvalidPage):
		return omni.BadRequest("INVALID_QUERY", "pagination is invalid").WithCause(err)
	default:
		// GoOmni masks unexpected errors; internal details stay in server logs.
		return err
	}
}