package api

import (
	"encoding/json"
	"errors"
	"net/http"

	"github.com/gin-gonic/gin"

	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
	"gitea.stevedudenhoeffer.com/steve/pansy/internal/service"
)

// plantCreateRequest is the body for POST /plants. spacingCm is centimeters;
// color is a hex string; icon is an emoji. daysToMaturity is optional.
type plantCreateRequest struct {
	Name           string  `json:"name" binding:"required"`
	Category       string  `json:"category" binding:"required"`
	SpacingCM      float64 `json:"spacingCm"`
	Color          string  `json:"color" binding:"required"`
	Icon           string  `json:"icon" binding:"required"`
	DaysToMaturity *int    `json:"daysToMaturity"`
	Notes          string  `json:"notes"`
}

func (r plantCreateRequest) toInput() service.PlantInput {
	return service.PlantInput{
		Name: r.Name, Category: r.Category, SpacingCM: r.SpacingCM,
		Color: r.Color, Icon: r.Icon, DaysToMaturity: r.DaysToMaturity, Notes: r.Notes,
	}
}

// plantUpdateRequest is the body for PATCH /plants/:id: every field optional
// (absent = unchanged), plus the required current version. daysToMaturity is
// json.RawMessage so an explicit null (clear it) is distinct from an absent
// field (unchanged).
type plantUpdateRequest struct {
	Name           *string         `json:"name"`
	Category       *string         `json:"category"`
	SpacingCM      *float64        `json:"spacingCm"`
	Color          *string         `json:"color"`
	Icon           *string         `json:"icon"`
	DaysToMaturity json.RawMessage `json:"daysToMaturity"`
	Notes          *string         `json:"notes"`
	Version        int64           `json:"version" binding:"required,min=1"`
}

func (r plantUpdateRequest) toPatch() (service.PlantPatch, error) {
	days, setDays, err := parseNullableInt(r.DaysToMaturity)
	if err != nil {
		return service.PlantPatch{}, err
	}
	return service.PlantPatch{
		Name: r.Name, Category: r.Category, SpacingCM: r.SpacingCM,
		Color: r.Color, Icon: r.Icon,
		SetDays: setDays, DaysToMaturity: days, Notes: r.Notes,
	}, nil
}

// parseNullableInt decodes a JSON number|null field into (value, present).
// Absent → (nil, false); null → (nil, true); 42 → (&42, true). A non-integer
// value is an error.
func parseNullableInt(raw json.RawMessage) (value *int, present bool, err error) {
	if len(raw) == 0 {
		return nil, false, nil
	}
	if err := json.Unmarshal(raw, &value); err != nil {
		return nil, false, err
	}
	return value, true, nil
}

func (h *handlers) listPlants(c *gin.Context) {
	plants, err := h.svc.ListPlants(c.Request.Context(), mustActor(c).ID)
	if err != nil {
		writeServiceError(c, err)
		return
	}
	c.JSON(http.StatusOK, plants)
}

func (h *handlers) createPlant(c *gin.Context) {
	var req plantCreateRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "name, category, color and icon are required")
		return
	}
	p, err := h.svc.CreatePlant(c.Request.Context(), mustActor(c).ID, req.toInput())
	if err != nil {
		writeServiceError(c, err)
		return
	}
	c.JSON(http.StatusCreated, p)
}

func (h *handlers) updatePlant(c *gin.Context) {
	id, ok := parseIDParam(c, "id")
	if !ok {
		return
	}
	var req plantUpdateRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "a current version is required")
		return
	}
	patch, err := req.toPatch()
	if err != nil {
		writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "invalid update payload")
		return
	}
	p, err := h.svc.UpdatePlant(c.Request.Context(), mustActor(c).ID, id, patch, req.Version)
	if err != nil {
		if errors.Is(err, domain.ErrVersionConflict) {
			writeVersionConflict(c, p)
			return
		}
		writeServiceError(c, err)
		return
	}
	c.JSON(http.StatusOK, p)
}

func (h *handlers) deletePlant(c *gin.Context) {
	id, ok := parseIDParam(c, "id")
	if !ok {
		return
	}
	if err := h.svc.DeletePlant(c.Request.Context(), mustActor(c).ID, id); err != nil {
		writeServiceError(c, err)
		return
	}
	c.Status(http.StatusNoContent)
}