package output

import (
	"encoding/json"
	"fmt"
	"os"

	"github.com/damirmukimov/city_resource_graph/models"
)

// Formatter handles different output formats
type Formatter struct {
	format string // "json", "summary", "table"
}

// NewFormatter creates a new formatter
func NewFormatter(format string) *Formatter {
	return &Formatter{format: format}
}

// FormatResult formats the calculation result based on the format type
func (f *Formatter) FormatResult(result *models.ModelResult) error {
	switch f.format {
	case "json":
		return f.formatJSON(result)
	case "summary":
		return f.formatSummary(result)
	default:
		return fmt.Errorf("unsupported format: %s", f.format)
	}
}

// formatJSON outputs the result as JSON
func (f *Formatter) formatJSON(result *models.ModelResult) error {
	encoder := json.NewEncoder(os.Stdout)
	encoder.SetIndent("", "  ")
	return encoder.Encode(result)
}

// formatSummary outputs a human-readable summary
func (f *Formatter) formatSummary(result *models.ModelResult) error {
	fmt.Println("=== Model Summary ===")
	fmt.Printf("Years calculated: %d\n", len(result.Years))
	fmt.Println()
	fmt.Println("Summary across all years:")
	fmt.Printf("  Total Revenue:    €%.2f\n", result.Summary.TotalRevenue)
	fmt.Printf("  Total Costs:      €%.2f\n", result.Summary.TotalCosts)
	fmt.Printf("  Total Profit:     €%.2f\n", result.Summary.TotalProfit)
	fmt.Printf("  Total CO₂ Avoided: %.2f t\n", result.Summary.TotalCO2Avoided)
	fmt.Printf("  Total Water Reused: %.2f m³\n", result.Summary.TotalWaterReused)
	fmt.Printf("  Total Waste Diverted: %.2f t\n", result.Summary.TotalWasteDiverted)
	fmt.Println()
	fmt.Println("Profitability Analysis:")
	fmt.Printf("  NPV (10%% discount): €%.2f\n", result.Profitability.NPV)
	fmt.Printf("  IRR:                 %.1f%%\n", result.Profitability.IRR)
	fmt.Printf("  Payback Period:      %.1f years\n", result.Profitability.PaybackPeriod)
	fmt.Println()
	fmt.Println("Year-by-year breakdown:")
	for _, year := range result.Years {
		fmt.Printf("\nYear %d:\n", year.Year)
		fmt.Printf("  Customers: %d total (%d paying)\n", year.Customer.TotalOrgs, year.Customer.PayingOrgs)
		fmt.Printf("  Revenue:   €%.2f (ARPU: €%.2f)\n", year.Revenue.Total, year.ARPU)
		fmt.Printf("  Costs:     €%.2f\n", year.Costs.Total)
		fmt.Printf("  Profit:    €%.2f (%.1f%% margin)\n", year.Profit, year.Margin)
		fmt.Printf("  Unit Economics: LTV €%.0f, CAC €%.0f, LTV/CAC %.1f:1\n",
			year.UnitEconomics.LTV.Blended, year.UnitEconomics.CAC, year.UnitEconomics.LTVToCACRatio)
		fmt.Printf("  CO₂ Avoided: %.2f t\n", year.Impact.CO2Avoided)

		if !year.Validation.IsValid() {
			fmt.Printf("  ⚠️  Validation warnings: %d\n", len(year.Validation.Errors))
			for _, err := range year.Validation.Errors {
				fmt.Printf("     - %s\n", err.Message)
			}
		}
	}
	return nil
}

// FormatValidation formats validation results
func (f *Formatter) FormatValidation(isValid bool, errors []error) error {
	if isValid {
		fmt.Println("✅ Parameters are valid")
		return nil
	}

	fmt.Println("❌ Validation failed:")
	for _, err := range errors {
		fmt.Printf("  - %v\n", err)
	}
	return nil
}