package game

import (
	"maps"
	"math"
	"slices"

	"github.com/google/uuid"
	e "github.com/iliadenisov/galaxy/internal/error"
)

type UpgradeCalc struct {
	Cost map[Tech]float64
}

func (uc UpgradeCalc) UpgradeCost(ships uint) float64 {
	var sum float64
	for v := range maps.Values(uc.Cost) {
		sum += v
	}
	return sum * float64(ships)
}

func (uc UpgradeCalc) UpgradeMaxShips(resources float64) uint {
	return uint(math.Floor(resources / uc.UpgradeCost(1)))
}

func BlockUpgradeCost(blockMass, currentBlockTech, targetBlockTech float64) float64 {
	if blockMass == 0 || targetBlockTech <= currentBlockTech {
		return 0
	}
	return (1 - currentBlockTech/targetBlockTech) * 10 * blockMass
}

func GroupUpgradeCost(sg ShipGroup, st ShipType, drive, weapons, shields, cargo float64) UpgradeCalc {
	uc := &UpgradeCalc{Cost: make(map[Tech]float64)}
	if drive > 0 {
		uc.Cost[TechDrive] = BlockUpgradeCost(st.DriveBlockMass(), sg.TechLevel(TechDrive), drive)
	}
	if weapons > 0 {
		uc.Cost[TechWeapons] = BlockUpgradeCost(st.WeaponsBlockMass(), sg.TechLevel(TechWeapons), weapons)
	}
	if shields > 0 {
		uc.Cost[TechShields] = BlockUpgradeCost(st.ShieldsBlockMass(), sg.TechLevel(TechShields), shields)
	}
	if cargo > 0 {
		uc.Cost[TechCargo] = BlockUpgradeCost(st.CargoBlockMass(), sg.TechLevel(TechCargo), cargo)
	}
	return *uc
}

func (g *Game) UpgradeGroup(raceName string, groupIndex uint, techInput string, limitShips uint, limitLevel float64) error {
	ri, err := g.raceIndex(raceName)
	if err != nil {
		return err
	}
	return g.upgradeGroupInternal(ri, groupIndex, techInput, limitShips, limitLevel)
}

func (g *Game) upgradeGroupInternal(ri int, groupIndex uint, techInput string, limitShips uint, limitLevel float64) error {
	sgi := -1
	for i, sg := range g.listIndexShipGroups(ri) {
		if sgi < 0 && sg.Index == groupIndex {
			sgi = i
		}
	}
	if sgi < 0 {
		return e.NewEntityNotExistsError("group #%d", groupIndex)
	}

	var sti int
	if sti = slices.IndexFunc(g.Race[ri].ShipTypes, func(st ShipType) bool { return st.ID == g.ShipGroups[sgi].TypeID }); sti < 0 {
		// hard to test, need manual game data invalidation
		return e.NewGameStateError("not found: ShipType ID=%v", g.ShipGroups[sgi].TypeID)
	}
	st := g.Race[ri].ShipTypes[sti]

	pl := slices.IndexFunc(g.Map.Planet, func(p Planet) bool { return p.Number == g.ShipGroups[sgi].Destination })
	if pl < 0 {
		return e.NewGameStateError("planet #%d", g.ShipGroups[sgi].Destination)
	}
	if g.Map.Planet[pl].Owner != uuid.Nil && g.Map.Planet[pl].Owner != g.Race[ri].ID {
		return e.NewEntityNotOwnedError("planet #%d for upgrade group #%d", g.Map.Planet[pl].Number, groupIndex)
	}

	if g.ShipGroups[sgi].State() != StateInOrbit && g.ShipGroups[sgi].State() != StateUpgrade {
		return e.NewShipsBusyError()
	}

	upgradeValidTech := map[string]Tech{
		TechDrive.String():   TechDrive,
		TechWeapons.String(): TechWeapons,
		TechShields.String(): TechShields,
		TechCargo.String():   TechCargo,
		TechAll.String():     TechAll,
	}

	techRequest, ok := upgradeValidTech[techInput]
	if !ok {
		return e.NewTechUnknownError(techInput)
	}

	var blockMasses map[Tech]float64 = map[Tech]float64{
		TechDrive:   st.DriveBlockMass(),
		TechWeapons: st.WeaponsBlockMass(),
		TechShields: st.ShieldsBlockMass(),
		TechCargo:   st.CargoBlockMass(),
	}

	switch {
	case techRequest != TechAll && blockMasses[techRequest] == 0:
		return e.NewUpgradeShipTechNotUsedError()
	case techRequest == TechAll && limitLevel != 0:
		return e.NewUpgradeParameterNotAllowedError("tech=%s max_level=%f", techRequest.String(), limitLevel)
	}

	targetLevel := make(map[Tech]float64)
	var sumLevels float64
	for _, tech := range []Tech{TechDrive, TechWeapons, TechShields, TechCargo} {
		if techRequest == TechAll || tech == techRequest {
			if g.Race[ri].TechLevel(tech) < limitLevel {
				return e.NewUpgradeTechLevelInsufficientError("%s=%.03f < %.03f", tech.String(), g.Race[ri].TechLevel(tech), limitLevel)
			}
			targetLevel[tech] = FutureUpgradeLevel(g.Race[ri].TechLevel(tech), g.ShipGroups[sgi].TechLevel(tech), limitLevel)
		} else {
			targetLevel[tech] = CurrentUpgradingLevel(g.ShipGroups[sgi], tech)
		}
		sumLevels += targetLevel[tech]
	}

	productionCapacity := PlanetProductionCapacity(g, g.Map.Planet[pl].Number)
	if g.ShipGroups[sgi].State() == StateUpgrade {
		// to calculate actual capacity we must substract upgrade cost of selected group, if is upgrade state
		productionCapacity -= g.ShipGroups[sgi].StateUpgrade.Cost()
	}
	uc := GroupUpgradeCost(g.ShipGroups[sgi], st, targetLevel[TechDrive], targetLevel[TechWeapons], targetLevel[TechShields], targetLevel[TechCargo])
	costForShip := uc.UpgradeCost(1)
	if costForShip == 0 {
		return e.NewUpgradeShipsAlreadyUpToDateError("%#v", targetLevel)
	}

	shipsToUpgrade := g.ShipGroups[sgi].Number
	// НЕ БОЛЕЕ УКАЗАННОГО
	if limitShips > 0 && shipsToUpgrade > limitShips {
		shipsToUpgrade = limitShips
	}

	maxUpgradableShips := uc.UpgradeMaxShips(productionCapacity)

	/*
		1. считаем стоимость модернизации одного корабля
		2. считаем сколько кораблей можно модернизировать
		3. если не хватает даже на 1 корабль, ограничиваемся одним кораблём и пересчитываем коэффициент пропорционально массе блоков
		4. иначе, считаем истинное количество кораблей с учётом ограничения maxShips
	*/
	blockMassSum := st.EmptyMass()

	coef := productionCapacity / costForShip
	if maxUpgradableShips == 0 {
		if limitLevel > 0 {
			return e.NewUpgradeInsufficientResourcesError("ship cost=%.03f L=%.03f", costForShip, productionCapacity)
		}
		sumLevels = sumLevels * coef
		for tech := range targetLevel {
			if blockMasses[tech] > 0 {
				proportional := sumLevels * (blockMasses[tech] / blockMassSum)
				targetLevel[tech] = proportional
			}
		}
		maxUpgradableShips = 1
	} else if maxUpgradableShips > shipsToUpgrade {
		maxUpgradableShips = shipsToUpgrade
	}

	// sanity check
	uc = GroupUpgradeCost(g.ShipGroups[sgi], st, targetLevel[TechDrive], targetLevel[TechWeapons], targetLevel[TechShields], targetLevel[TechCargo])
	costForGroup := uc.UpgradeCost(maxUpgradableShips)
	if costForGroup > productionCapacity {
		e.NewGameStateError("cost recalculation: coef=%f cost(%d)=%f L=%f", coef, maxUpgradableShips, costForGroup, productionCapacity)
	}

	// break group if needed
	if maxUpgradableShips < g.ShipGroups[sgi].Number {
		if g.ShipGroups[sgi].State() == StateUpgrade {
			return e.NewUpgradeGroupBreakNotAllowedError("ships=%d max=%d", g.ShipGroups[sgi].Number, maxUpgradableShips)
		}
		nsgi, err := g.breakGroupSafe(ri, groupIndex, maxUpgradableShips)
		if err != nil {
			return err
		}
		sgi = nsgi
	}

	// finally, fill group upgrade prefs
	for tech := range targetLevel {
		if targetLevel[tech] > 0 {
			g.ShipGroups[sgi] = UpgradeGroupPreference(g.ShipGroups[sgi], st, tech, targetLevel[tech])
		}
	}

	return nil
}

func CurrentUpgradingLevel(sg ShipGroup, tech Tech) float64 {
	if sg.StateUpgrade == nil {
		return 0
	}
	ti := slices.IndexFunc(sg.StateUpgrade.UpgradeTech, func(pref UpgradePreference) bool { return pref.Tech == tech })
	if ti >= 0 {
		return sg.StateUpgrade.UpgradeTech[ti].Level
	}
	return 0
}

func FutureUpgradeLevel(raceLevel, groupLevel, limit float64) float64 {
	target := limit
	if target == 0 || target > raceLevel {
		target = raceLevel
	}
	if groupLevel == target {
		return 0
	}
	return target
}

func UpgradeGroupPreference(sg ShipGroup, st ShipType, tech Tech, v float64) ShipGroup {
	if v <= 0 || st.BlockMass(tech) == 0 || sg.TechLevel(tech) >= v {
		return sg
	}
	var su InUpgrade
	if sg.StateUpgrade != nil {
		su = *sg.StateUpgrade
	} else {
		su = InUpgrade{UpgradeTech: []UpgradePreference{}}
	}
	ti := slices.IndexFunc(su.UpgradeTech, func(pref UpgradePreference) bool { return pref.Tech == tech })
	if ti < 0 {
		su.UpgradeTech = append(su.UpgradeTech, UpgradePreference{Tech: tech})
		ti = len(su.UpgradeTech) - 1
	}
	su.UpgradeTech[ti].Level = v
	su.UpgradeTech[ti].Cost = BlockUpgradeCost(st.BlockMass(tech), sg.TechLevel(tech), v) * float64(sg.Number)

	sg.StateUpgrade = &su
	return sg
}