package handler

import (
	"strconv"

	"accounting-app/pkg/api"
	"accounting-app/internal/models"
	"accounting-app/internal/service"

	"github.com/gin-gonic/gin"
)

// AllocationRuleHandler handles HTTP requests for allocation rule operations
type AllocationRuleHandler struct {
	service *service.AllocationRuleService
}

// NewAllocationRuleHandler creates a new AllocationRuleHandler instance
func NewAllocationRuleHandler(service *service.AllocationRuleService) *AllocationRuleHandler {
	return &AllocationRuleHandler{
		service: service,
	}
}

// RegisterRoutes registers allocation rule-related routes
func (h *AllocationRuleHandler) RegisterRoutes(rg *gin.RouterGroup) {
	allocationRules := rg.Group("/allocation-rules")
	{
		allocationRules.POST("", h.CreateAllocationRule)
		allocationRules.GET("", h.GetAllAllocationRules)
		allocationRules.GET("/suggest", h.SuggestAllocationForIncome)
		allocationRules.GET("/:id", h.GetAllocationRule)
		allocationRules.PUT("/:id", h.UpdateAllocationRule)
		allocationRules.DELETE("/:id", h.DeleteAllocationRule)
		allocationRules.POST("/:id/apply", h.ApplyAllocationRule)
	}
}

// CreateAllocationRule handles POST /api/v1/allocation-rules
func (h *AllocationRuleHandler) CreateAllocationRule(c *gin.Context) {
	var input service.AllocationRuleInput
	if err := c.ShouldBindJSON(&input); err != nil {
		api.ValidationError(c, err.Error())
		return
	}

	// Get user ID from context
	userID, exists := c.Get("user_id")
	if !exists {
		api.Unauthorized(c, "User not authenticated")
		return
	}
	input.UserID = userID.(uint)

	rule, err := h.service.CreateAllocationRule(input)
	if err != nil {
		switch err {
		case service.ErrInvalidTriggerType:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidTargetType:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidAllocationPercentage:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidAllocationAmount:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidAllocationTarget:
			api.BadRequest(c, err.Error())
		case service.ErrTotalPercentageExceeds100:
			api.BadRequest(c, err.Error())
		case service.ErrTargetNotFound:
			api.BadRequest(c, err.Error())
		default:
			api.InternalError(c, "Failed to create allocation rule")
		}
		return
	}

	api.Created(c, rule)
}

// GetAllocationRule handles GET /api/v1/allocation-rules/:id
func (h *AllocationRuleHandler) GetAllocationRule(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 32)
	if err != nil {
		api.BadRequest(c, "Invalid allocation rule ID")
		return
	}

	// Get user ID from context
	userID, exists := c.Get("user_id")
	if !exists {
		api.Unauthorized(c, "User not authenticated")
		return
	}

	rule, err := h.service.GetAllocationRule(userID.(uint), uint(id))
	if err != nil {
		if err == service.ErrAllocationRuleNotFound {
			api.NotFound(c, "Allocation rule not found")
			return
		}
		api.InternalError(c, "Failed to get allocation rule")
		return
	}

	api.Success(c, rule)
}

// GetAllAllocationRules handles GET /api/v1/allocation-rules
func (h *AllocationRuleHandler) GetAllAllocationRules(c *gin.Context) {
	// Check if we should filter by active status
	activeOnly := c.Query("active") == "true"

	var rules []models.AllocationRule
	var err error

	// Get user ID from context
	userID, exists := c.Get("user_id")
	if !exists {
		api.Unauthorized(c, "User not authenticated")
		return
	}

	if activeOnly {
		rules, err = h.service.GetActiveAllocationRules(userID.(uint))
	} else {
		rules, err = h.service.GetAllAllocationRules(userID.(uint))
	}

	if err != nil {
		api.InternalError(c, "Failed to get allocation rules")
		return
	}

	api.Success(c, rules)
}

// UpdateAllocationRule handles PUT /api/v1/allocation-rules/:id
func (h *AllocationRuleHandler) UpdateAllocationRule(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 32)
	if err != nil {
		api.BadRequest(c, "Invalid allocation rule ID")
		return
	}

	var input service.AllocationRuleInput
	if err := c.ShouldBindJSON(&input); err != nil {
		api.ValidationError(c, err.Error())
		return
	}

	// Get user ID from context
	userID, exists := c.Get("user_id")
	if !exists {
		api.Unauthorized(c, "User not authenticated")
		return
	}
	input.UserID = userID.(uint)

	rule, err := h.service.UpdateAllocationRule(userID.(uint), uint(id), input)
	if err != nil {
		switch err {
		case service.ErrAllocationRuleNotFound:
			api.NotFound(c, "Allocation rule not found")
		case service.ErrInvalidTriggerType:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidTargetType:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidAllocationPercentage:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidAllocationAmount:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidAllocationTarget:
			api.BadRequest(c, err.Error())
		case service.ErrTotalPercentageExceeds100:
			api.BadRequest(c, err.Error())
		case service.ErrTargetNotFound:
			api.BadRequest(c, err.Error())
		default:
			api.InternalError(c, "Failed to update allocation rule")
		}
		return
	}

	api.Success(c, rule)
}

// DeleteAllocationRule handles DELETE /api/v1/allocation-rules/:id
func (h *AllocationRuleHandler) DeleteAllocationRule(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 32)
	if err != nil {
		api.BadRequest(c, "Invalid allocation rule ID")
		return
	}

	// Get user ID from context
	userID, exists := c.Get("user_id")
	if !exists {
		api.Unauthorized(c, "User not authenticated")
		return
	}

	err = h.service.DeleteAllocationRule(userID.(uint), uint(id))
	if err != nil {
		switch err {
		case service.ErrAllocationRuleNotFound:
			api.NotFound(c, "Allocation rule not found")
		case service.ErrAllocationRuleInUse:
			api.Conflict(c, err.Error())
		default:
			api.InternalError(c, "Failed to delete allocation rule")
		}
		return
	}

	api.NoContent(c)
}

// ApplyAllocationRule handles POST /api/v1/allocation-rules/:id/apply
func (h *AllocationRuleHandler) ApplyAllocationRule(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 32)
	if err != nil {
		api.BadRequest(c, "Invalid allocation rule ID")
		return
	}

	var input service.ApplyAllocationInput
	if err := c.ShouldBindJSON(&input); err != nil {
		api.ValidationError(c, err.Error())
		return
	}

	// Get user ID from context
	userID, exists := c.Get("user_id")
	if !exists {
		api.Unauthorized(c, "User not authenticated")
		return
	}

	result, err := h.service.ApplyAllocationRule(userID.(uint), uint(id), input)
	if err != nil {
		switch err {
		case service.ErrAllocationRuleNotFound:
			api.NotFound(c, "Allocation rule not found")
		case service.ErrInsufficientAmount:
			api.BadRequest(c, err.Error())
		case service.ErrAccountNotFound:
			api.BadRequest(c, err.Error())
		case service.ErrInsufficientBalance:
			api.BadRequest(c, err.Error())
		case service.ErrTargetNotFound:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidTargetType:
			api.BadRequest(c, err.Error())
		case service.ErrInvalidAllocationTarget:
			api.BadRequest(c, err.Error())
		default:
			api.InternalError(c, "Failed to apply allocation rule")
		}
		return
	}

	api.Success(c, result)
}

// SuggestAllocationForIncome handles GET /api/v1/allocation-rules/suggest
func (h *AllocationRuleHandler) SuggestAllocationForIncome(c *gin.Context) {
	// Get amount from query parameter
	amountStr := c.Query("amount")
	if amountStr == "" {
		api.BadRequest(c, "Amount parameter is required")
		return
	}

	amount, err := strconv.ParseFloat(amountStr, 64)
	if err != nil || amount <= 0 {
		api.BadRequest(c, "Invalid amount")
		return
	}

	// Get account_id from query parameter
	accountIDStr := c.Query("account_id")
	if accountIDStr == "" {
		api.BadRequest(c, "account_id parameter is required")
		return
	}

	accountID, err := strconv.ParseUint(accountIDStr, 10, 32)
	if err != nil {
		api.BadRequest(c, "Invalid account_id")
		return
	}

	// Get user ID from context
	userID, exists := c.Get("user_id")
	if !exists {
		api.Unauthorized(c, "User not authenticated")
		return
	}

	rules, err := h.service.SuggestAllocationForIncome(userID.(uint), amount, uint(accountID))
	if err != nil {
		api.InternalError(c, "Failed to get allocation suggestions")
		return
	}

	api.Success(c, rules)
}