package services

import (
	"strings"

	"git.mchus.pro/mchus/quoteforge/internal/localdb"
	"git.mchus.pro/mchus/quoteforge/internal/models"
)

// RentalService computes paid-testing/rental pricing for a configuration,
// per the draft "Регламент расчёта стоимости платного тестирования и аренды
// GPU-серверов" methodology (Steps 1-8 and 10; buyout/Step 9 is out of scope).
//
// Pricing is always quoted per week (Разовый + Еженедельный): the methodology
// prices in multiples of a week, and there is no separate "term" input — a
// sales rep multiplies the weekly rate by however many weeks are needed.
//
// The "Цена" the methodology depreciates against is derived from the
// configuration's existing Estimate buy price via a single project-wide
// uplift percentage — QuoteForge has no per-component sale price today.
//
// Support is out of scope here: this calc covers BOM component depreciation
// only. If a deal needs support priced in, that is handled outside the
// Аренда tab (e.g. via the Estimate tab / support pricing elsewhere) rather
// than being computed or added here.
type RentalService struct {
	localDB *localdb.LocalDB
}

func NewRentalService(localDB *localdb.LocalDB) *RentalService {
	return &RentalService{localDB: localDB}
}

const (
	daysPerYear        = 365
	rentalMarginFactor = 1.03
	rentalVATFactor    = 1.22
	rentalWeekDays     = 7
)

// rentalCoeffs holds the depreciation coefficients for one methodology category.
type rentalCoeffs struct {
	KNew         float64 // one-time layer-1 hit, new hardware only
	LifeNewDays  float64
	LifeUsedDays float64
}

var (
	chassisCoeffs       = rentalCoeffs{KNew: 0.30, LifeNewDays: 5 * daysPerYear, LifeUsedDays: 3 * daysPerYear}
	cpuDramCoeffs       = rentalCoeffs{KNew: 0.075, LifeNewDays: 5 * daysPerYear, LifeUsedDays: 3 * daysPerYear}
	diskCoeffs          = rentalCoeffs{KNew: 0.50, LifeNewDays: 5 * daysPerYear, LifeUsedDays: 3 * daysPerYear}
	cardsCoeffs         = rentalCoeffs{KNew: 0.30, LifeNewDays: 5 * daysPerYear, LifeUsedDays: 3 * daysPerYear}
	gpuActualCoeffs     = rentalCoeffs{KNew: 0.20, LifeNewDays: 2 * daysPerYear, LifeUsedDays: 1 * daysPerYear}
	gpuStabilizedCoeffs = rentalCoeffs{KNew: 0.20, LifeNewDays: 3 * daysPerYear, LifeUsedDays: 1 * daysPerYear}
)

// categoryCoeffMap maps existing lot_category codes (models.DefaultCategories)
// to their methodology category. Categories absent here (including "Other")
// fall back to cardsCoeffs as the closest generic fit.
var categoryCoeffMap = map[string]rentalCoeffs{
	"BB":  chassisCoeffs,
	"MB":  chassisCoeffs,
	"PSU": chassisCoeffs,
	"PS":  chassisCoeffs,

	"CPU": cpuDramCoeffs,
	"MEM": cpuDramCoeffs,

	"SSD":   diskCoeffs,
	"HDD":   diskCoeffs,
	"M2":    diskCoeffs,
	"EDSFF": diskCoeffs,
	"HHHL":  diskCoeffs,

	"NIC":    cardsCoeffs,
	"HCA":    cardsCoeffs,
	"DPU":    cardsCoeffs,
	"HBA":    cardsCoeffs,
	"RAID":   cardsCoeffs,
	"RISERS": cardsCoeffs,
	"CARD":   cardsCoeffs,
	"ACC":    cardsCoeffs,
}

// gpuActualGenSubstrings identifies "actual generation" GPUs per the
// regulation's model list (H200, RTX PRO 6000 Blackwell SE, B200/B300).
// Update manually as new GPU generations ship.
var gpuActualGenSubstrings = []string{"H200", "B200", "B300", "BLACKWELL SE"}

func rentalCoeffsFor(category, lotName string) rentalCoeffs {
	cat := strings.ToUpper(strings.TrimSpace(category))
	if cat == "GPU" {
		upperLot := strings.ToUpper(lotName)
		for _, s := range gpuActualGenSubstrings {
			if strings.Contains(upperLot, s) {
				return gpuActualCoeffs
			}
		}
		return gpuStabilizedCoeffs
	}
	if c, ok := categoryCoeffMap[cat]; ok {
		return c
	}
	return cardsCoeffs
}

type RentalComponentResult struct {
	LotName      string  `json:"lot_name"`
	Category     string  `json:"category"`
	Quantity     int     `json:"quantity"`
	Condition    string  `json:"condition"`
	BuyPrice     float64 `json:"buy_price"`  // per-unit Estimate price
	Price        float64 `json:"price"`      // per-unit "Цена" after uplift
	Layer1       float64 `json:"layer1"`     // total for quantity, ex-VAT, no margin
	DailyWear    float64 `json:"daily_wear"` // total for quantity, ex-VAT, no margin
	OneTime      float64 `json:"one_time"`   // Разовый, with margin+VAT
	Weekly       float64 `json:"weekly"`     // Еженедельный, with margin+VAT
	PriceMissing bool    `json:"price_missing"`
}

type RentalCalculateResult struct {
	Items          []RentalComponentResult `json:"items"`
	Layer1Total    float64                 `json:"layer1_total"`
	DailyWearTotal float64                 `json:"daily_wear_total"`
	OneTimeTotal   float64                 `json:"one_time_total"` // Разовый, with margin+VAT
	WeeklyTotal    float64                 `json:"weekly_total"`   // Еженедельный, with margin+VAT
	Warnings       []string                `json:"warnings,omitempty"`
}

// Calculate computes rental pricing for a configuration, always priced per
// week (Разовый one-time + Еженедельный recurring).
func (s *RentalService) Calculate(configUUID string, req *RentalUpdateRequest) (*RentalCalculateResult, error) {
	localCfg, err := s.localDB.GetConfigurationByUUID(configUUID)
	if err != nil {
		return nil, ErrConfigNotFound
	}

	conditionByLot := make(map[string]string, len(req.Items))
	for _, item := range req.Items {
		conditionByLot[models.NormalizeLotName(item.LotName)] = item.Condition
	}

	lotNames := make([]string, 0, len(localCfg.Items))
	for _, item := range localCfg.Items {
		lotNames = append(lotNames, item.LotName)
	}
	var categories map[string]string
	if localCfg.PricelistID != nil {
		categories, _ = s.localDB.GetLocalLotCategoriesByServerPricelistID(*localCfg.PricelistID, lotNames)
	}
	if categories == nil {
		categories = map[string]string{}
	}

	result := &RentalCalculateResult{
		Items: make([]RentalComponentResult, 0, len(localCfg.Items)),
	}

	uplift := 1 + req.UpliftPercent/100

	for _, item := range localCfg.Items {
		condition := conditionByLot[item.LotName]
		if condition != "used" {
			condition = "new"
		}
		category := categories[item.LotName]
		coeffs := rentalCoeffsFor(category, item.LotName)

		price := item.UnitPrice * uplift
		qty := float64(item.Quantity)

		var layer1, residual, term float64
		if condition == "new" {
			layer1 = price * coeffs.KNew * qty
			residual = (price - price*coeffs.KNew) * qty
			term = coeffs.LifeNewDays
		} else {
			layer1 = 0
			residual = price * qty
			term = coeffs.LifeUsedDays
		}
		dailyWear := 0.0
		if term > 0 {
			dailyWear = residual / term
		}

		result.Layer1Total += layer1
		result.DailyWearTotal += dailyWear

		oneTime := layer1 * rentalMarginFactor * rentalVATFactor
		weekly := dailyWear * rentalWeekDays * rentalMarginFactor * rentalVATFactor

		result.Items = append(result.Items, RentalComponentResult{
			LotName:      item.LotName,
			Category:     category,
			Quantity:     item.Quantity,
			Condition:    condition,
			BuyPrice:     item.UnitPrice,
			Price:        price,
			Layer1:       layer1,
			DailyWear:    dailyWear,
			OneTime:      oneTime,
			Weekly:       weekly,
			PriceMissing: item.UnitPrice <= 0,
		})
	}

	result.OneTimeTotal = result.Layer1Total * rentalMarginFactor * rentalVATFactor
	result.WeeklyTotal = result.DailyWearTotal * rentalWeekDays * rentalMarginFactor * rentalVATFactor

	return result, nil
}