package customer

import (
	"github.com/damirmukimov/city_resource_graph/models/params"
)

// CustomerMetrics represents customer adoption metrics for a given year.
type CustomerMetrics struct {
	TotalOrgs       int     `json:"total_orgs"`       // Total active organizations (after churn)
	PayingOrgs      int     `json:"paying_orgs"`      // Active paying organizations
	FreeOrgs        int     `json:"free_orgs"`        // Active free tier organizations
	PayingShare     float64 `json:"paying_share"`     // Percentage paying (0.0-1.0)
	NewAcquisitions int     `json:"new_acquisitions"` // New organizations acquired this year
	ChurnedOrgs     int     `json:"churned_orgs"`     // Organizations that churned this year
	CumulativeOrgs  int     `json:"cumulative_orgs"`  // Cumulative organizations ever acquired
}

// TierDistribution represents the distribution of paying customers across tiers.
type TierDistribution struct {
	Basic      int `json:"basic"`      // Number of Basic tier customers
	Business   int `json:"business"`   // Number of Business tier customers
	Enterprise int `json:"enterprise"` // Number of Enterprise tier customers
	Total      int `json:"total"`      // Total paying customers
}

// ChurnMetrics represents churn and retention metrics per tier.
type ChurnMetrics struct {
	Basic      TierChurn `json:"basic"`
	Business   TierChurn `json:"business"`
	Enterprise TierChurn `json:"enterprise"`
}

// TierChurn represents churn metrics for a single tier.
type TierChurn struct {
	AnnualChurn       float64 `json:"annual_churn"`        // Annual churn rate (0.0-1.0)
	Retention         float64 `json:"retention"`           // Retention rate (1.0 - churn)
	AvgLifetimeMonths int     `json:"avg_lifetime_months"` // Average customer lifetime in months
}

// DefaultChurnMetrics returns default churn metrics per tier.
func DefaultChurnMetrics() ChurnMetrics {
	return ChurnMetrics{
		Basic: TierChurn{
			AnnualChurn:       0.15, // 15%
			Retention:         0.85, // 85%
			AvgLifetimeMonths: 48,   // 4 years (conservative)
		},
		Business: TierChurn{
			AnnualChurn:       0.10, // 10%
			Retention:         0.90, // 90%
			AvgLifetimeMonths: 64,   // 5.3 years (conservative)
		},
		Enterprise: TierChurn{
			AnnualChurn:       0.05, // 5%
			Retention:         0.95, // 95%
			AvgLifetimeMonths: 80,   // 6.7 years (conservative)
		},
	}
}

// CalculateCustomerMetrics computes customer adoption metrics for a given year.
func CalculateCustomerMetrics(year int, p *params.Params) CustomerMetrics {
	totalOrgs := p.Adoption.TotalOrgs.GetYear(year)
	payingShare := p.Adoption.PayingShare.GetYear(year)

	payingOrgs := int(float64(totalOrgs) * payingShare)
	freeOrgs := totalOrgs - payingOrgs

	// For churn modeling, estimate new acquisitions vs cumulative
	// In a simplified model, assume all customers are "new" for the target year
	// Churn rates are used in LTV calculations rather than reducing active customers
	newAcquisitions := totalOrgs
	churnedOrgs := 0            // Not modeled as reducing active base in this simplified approach
	cumulativeOrgs := totalOrgs // Simplified - doesn't track across years

	return CustomerMetrics{
		TotalOrgs:       totalOrgs,
		PayingOrgs:      payingOrgs,
		FreeOrgs:        freeOrgs,
		PayingShare:     payingShare,
		NewAcquisitions: newAcquisitions,
		ChurnedOrgs:     churnedOrgs,
		CumulativeOrgs:  cumulativeOrgs,
	}
}

// CalculateTierDistribution computes the distribution of paying customers across tiers.
func CalculateTierDistribution(year int, payingOrgs int, p *params.Params) TierDistribution {
	tierMix := p.Pricing.TierMix.GetYear(year)

	basic := int(float64(payingOrgs) * tierMix.Basic)
	business := int(float64(payingOrgs) * tierMix.Business)
	enterprise := int(float64(payingOrgs) * tierMix.Enterprise)

	// Handle rounding - ensure total matches
	total := basic + business + enterprise
	if total != payingOrgs {
		// Adjust basic tier to account for rounding differences
		basic += payingOrgs - total
	}

	return TierDistribution{
		Basic:      basic,
		Business:   business,
		Enterprise: enterprise,
		Total:      payingOrgs,
	}
}