package handler

import (
	"time"

	"github.com/gin-gonic/gin"

	"github.com/kennethcheng/fuellog-api/internal/dto"
	"github.com/kennethcheng/fuellog-api/internal/model"
	"github.com/kennethcheng/fuellog-api/internal/service"
)

// RefuelHandler 加油记录路由。
type RefuelHandler struct{ svc service.RefuelRecordService }

func NewRefuelHandler(svc service.RefuelRecordService) *RefuelHandler {
	return &RefuelHandler{svc: svc}
}

// POST /api/refuels
func (h *RefuelHandler) Create(c *gin.Context) {
	var in dto.RefuelCreate
	if err := bindJSON(c, &in); err != nil {
		writeError(c, err)
		return
	}
	rec, err := h.svc.Create(c.Request.Context(), &in)
	if err != nil {
		writeError(c, err)
		return
	}
	sendJSON(c, rec)
}

// GET /api/refuels/:id
func (h *RefuelHandler) Get(c *gin.Context) {
	id, err := parseUint64(c, "id")
	if err != nil {
		writeError(c, err)
		return
	}
	rec, err := h.svc.Get(c.Request.Context(), id)
	if err != nil {
		writeError(c, err)
		return
	}
	sendJSON(c, rec)
}

// PUT /api/refuels/:id
func (h *RefuelHandler) Update(c *gin.Context) {
	id, err := parseUint64(c, "id")
	if err != nil {
		writeError(c, err)
		return
	}
	var in dto.RefuelUpdate
	if err := bindJSON(c, &in); err != nil {
		writeError(c, err)
		return
	}
	rec, err := h.svc.Update(c.Request.Context(), id, &in)
	if err != nil {
		writeError(c, err)
		return
	}
	sendJSON(c, rec)
}

// DELETE /api/refuels/:id
func (h *RefuelHandler) Delete(c *gin.Context) {
	id, err := parseUint64(c, "id")
	if err != nil {
		writeError(c, err)
		return
	}
	if err := h.svc.Delete(c.Request.Context(), id); err != nil {
		writeError(c, err)
		return
	}
	c.Status(204)
}

// GET /api/refuels?vehicle_id=...&start_date=...&end_date=...
func (h *RefuelHandler) List(c *gin.Context) {
	vehicleIDStr := c.Query("vehicle_id")
	if vehicleIDStr == "" {
		writeError(c, errInvalidVehicleID())
		return
	}
	vehicleID, err := parseUint64Query(vehicleIDStr)
	if err != nil {
		writeError(c, err)
		return
	}
	var startPtr, endPtr *time.Time
	if s := c.Query("start_date"); s != "" {
		t, err := time.Parse(time.RFC3339, s)
		if err != nil {
			writeError(c, errInvalid("start_date 需为 RFC3339 时间"))
			return
		}
		startPtr = &t
	}
	if s := c.Query("end_date"); s != "" {
		t, err := time.Parse(time.RFC3339, s)
		if err != nil {
			writeError(c, errInvalid("end_date 需为 RFC3339 时间"))
			return
		}
		endPtr = &t
	}
	records, err := h.svc.ListByVehicle(c.Request.Context(), vehicleID, startPtr, endPtr)
	if err != nil {
		writeError(c, err)
		return
	}
	if records == nil {
		records = []model.RefuelRecord{}
	}
	sendJSON(c, records)
}

// GET /api/vehicles/:id/statistics
func (h *RefuelHandler) Statistics(c *gin.Context) {
	vehicleID, err := parseUint64(c, "id")
	if err != nil {
		writeError(c, err)
		return
	}
	stats, err := h.svc.Statistics(c.Request.Context(), vehicleID)
	if err != nil {
		writeError(c, err)
		return
	}
	sendJSON(c, stats)
}

func parseUint64Query(s string) (uint64, error) {
	v, err := parseUint64Impl(s)
	if err != nil {
		return 0, errInvalid("vehicle_id 必须是正整数")
	}
	return v, nil
}

func parseUint64Impl(s string) (uint64, error) {
	var v uint64
	for _, c := range s {
		if c < '0' || c > '9' {
			return 0, errInvalid("非数字字符")
		}
		v = v*10 + uint64(c-'0')
	}
	if v == 0 {
		return 0, errInvalid("id 不能为 0")
	}
	return v, nil
}