package admin

import (
	"net/http"
	"strconv"

	"github.com/gin-gonic/gin"
	"github.com/shopspring/decimal"
	"go.uber.org/zap"
	"gorm.io/gorm"

	"openteam/server/internal/billing"
	"openteam/server/internal/pkg/httpx"
	"openteam/server/internal/store"
)

type userHandler struct {
	db     *gorm.DB
	bill   *billing.Service
	log    *zap.Logger
}

// List handles GET /api/v1/admin/users?page&search.
func (h *userHandler) List(c *gin.Context) {
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	if page < 1 {
		page = 1
	}
	pageSize := 20
	search := c.Query("search")

	q := h.db.Model(&store.User{})
	if search != "" {
		like := "%" + search + "%"
		q = q.Where("username LIKE ? OR email LIKE ?", like, like)
	}
	var total int64
	q.Count(&total)

	var users []store.User
	if err := q.Order("id DESC").Offset((page - 1) * pageSize).Limit(pageSize).Find(&users).Error; err != nil {
		h.log.Warn("list users failed", zap.Error(err))
		httpx.Fail(c, http.StatusInternalServerError, "list users failed")
		return
	}
	out := make([]gin.H, 0, len(users))
	for i := range users {
		out = append(out, userDTO(&users[i]))
	}
	httpx.OK(c, gin.H{"total": total, "page": page, "items": out})
}

// Update handles PATCH /api/v1/admin/users/:id.
func (h *userHandler) Update(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		httpx.Fail(c, http.StatusBadRequest, "invalid user id")
		return
	}
	var u store.User
	if err := h.db.First(&u, id).Error; err != nil {
		httpx.Fail(c, http.StatusNotFound, "user not found")
		return
	}
	var in struct {
		Role   *string `json:"role"`
		Status *string `json:"status"`
	}
	if !httpx.Bind(c, &in) {
		return
	}
	updates := map[string]any{}
	if in.Role != nil {
		if *in.Role != "admin" && *in.Role != "user" {
			httpx.Fail(c, http.StatusBadRequest, "invalid role")
			return
		}
		updates["role"] = *in.Role
	}
	if in.Status != nil {
		if *in.Status != "active" && *in.Status != "disabled" {
			httpx.Fail(c, http.StatusBadRequest, "invalid status")
			return
		}
		updates["status"] = *in.Status
	}
	if len(updates) > 0 {
		if err := h.db.Model(&u).Updates(updates).Error; err != nil {
			h.log.Warn("update user failed", zap.Error(err))
			httpx.Fail(c, http.StatusInternalServerError, "update user failed")
			return
		}
	}
	h.db.First(&u, id)
	httpx.OK(c, userDTO(&u))
}

// AdjustBalance handles POST /api/v1/admin/users/:id/balance.
func (h *userHandler) AdjustBalance(c *gin.Context) {
	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		httpx.Fail(c, http.StatusBadRequest, "invalid user id")
		return
	}
	var in struct {
		Amount string `json:"amount" binding:"required"`
		Remark string `json:"remark"`
	}
	if !httpx.Bind(c, &in) {
		return
	}
	amount, err := decimal.NewFromString(in.Amount)
	if err != nil {
		httpx.Fail(c, http.StatusBadRequest, "invalid amount")
		return
	}
	if amount.IsZero() {
		httpx.Fail(c, http.StatusBadRequest, "amount must be non-zero")
		return
	}
	after, err := h.bill.AdminAdjust(id, amount.Round(8), in.Remark)
	if err != nil {
		if err == billing.ErrInsufficientBalance {
			httpx.Fail(c, http.StatusBadRequest, "amount would make balance negative")
			return
		}
		h.log.Warn("adjust balance failed", zap.Error(err))
		httpx.Fail(c, http.StatusInternalServerError, "adjust balance failed")
		return
	}
	httpx.OK(c, gin.H{"balanceAfter": after.String()})
}

func userDTO(u *store.User) gin.H {
	return gin.H{
		"id": u.ID, "username": u.Username, "email": u.Email,
		"role": u.Role, "balance": u.Balance.String(), "status": u.Status,
		"lastLoginAt": u.LastLoginAt, "createdAt": u.CreatedAt,
	}
}