package ports

import (
	"context"
	"fmt"
	"strings"

	"galaxy/lobby/internal/domain/common"
)

// PlayerObservedStats stores one decoded `player_turn_stats` element from a
// Game Master event. The fields mirror the wire format documented in
// lobby/README.md §Runtime Snapshot. Counts are non-negative cumulative
// totals reported by the engine for the named user at the time the event
// was emitted.
type PlayerObservedStats struct {
	// UserID identifies the platform user the stats line belongs to.
	UserID string

	// Planets stores the cumulative number of planets controlled by the
	// user at observation time.
	Planets int64

	// Population stores the cumulative population owned by the user at
	// observation time.
	Population int64

	// ShipsBuilt stores the cumulative ships-built counter for the user
	// at observation time.
	ShipsBuilt int64
}

// Validate reports whether stats contain the structural invariants required
// by GameTurnStatsStore methods.
func (stats PlayerObservedStats) Validate() error {
	if strings.TrimSpace(stats.UserID) == "" {
		return fmt.Errorf("player turn stats: user id must not be empty")
	}
	if stats.Planets < 0 {
		return fmt.Errorf("player turn stats: planets must not be negative")
	}
	if stats.Population < 0 {
		return fmt.Errorf("player turn stats: population must not be negative")
	}
	if stats.ShipsBuilt < 0 {
		return fmt.Errorf("player turn stats: ships built must not be negative")
	}
	return nil
}

// PlayerInitialStats is an alias for PlayerObservedStats. Game Lobby
// Service freezes the first observation per user as that user's initial
// values; the wire format is identical, only the persistence semantics
// differ.
type PlayerInitialStats = PlayerObservedStats

// PlayerStatsAggregate stores the per-user aggregate maintained by
// GameTurnStatsStore for one game. Initial fields are frozen at the first
// SaveInitial call for the user; max fields are updated by per-component
// maximum on each UpdateMax call.
type PlayerStatsAggregate struct {
	// UserID identifies the platform user the aggregate belongs to.
	UserID string

	// InitialPlanets stores the user's planets count from the first
	// observation, frozen for the lifetime of the game.
	InitialPlanets int64

	// InitialPopulation stores the user's population from the first
	// observation, frozen for the lifetime of the game.
	InitialPopulation int64

	// InitialShipsBuilt stores the user's ships-built counter from the
	// first observation, frozen for the lifetime of the game.
	InitialShipsBuilt int64

	// MaxPlanets stores the running maximum planets count observed for
	// the user across the lifetime of the game.
	MaxPlanets int64

	// MaxPopulation stores the running maximum population observed for
	// the user across the lifetime of the game.
	MaxPopulation int64

	// MaxShipsBuilt stores the running maximum ships-built counter
	// observed for the user across the lifetime of the game.
	MaxShipsBuilt int64
}

// GameTurnStatsAggregate stores every PlayerStatsAggregate for one game.
// The slice is empty when no SaveInitial call has succeeded yet.
type GameTurnStatsAggregate struct {
	// GameID identifies the game the aggregate belongs to.
	GameID common.GameID

	// Players stores the per-user aggregates ordered by UserID ascending.
	Players []PlayerStatsAggregate
}

// GameTurnStatsStore stores per-game per-user initial and running-maximum
// stats derived from Game Master `runtime_snapshot_update` events. The
// aggregate is read once by capability evaluation at game finish and then
// deleted (see lobby/README.md §Runtime Snapshot).
//
// Adapters must keep the initial fields frozen against later SaveInitial
// calls and must keep the max fields monotonically non-decreasing on every
// UpdateMax call. All methods are safe to call concurrently for the same
// gameID.
type GameTurnStatsStore interface {
	// SaveInitial freezes the initial fields for every user in stats.
	// Subsequent calls for the same (gameID, user_id) tuple do not
	// overwrite the stored initial values; they return nil so workers
	// may call SaveInitial on every received event without bookkeeping.
	// The first call for a user also primes the max fields with the same
	// values so a single observation is reflected by both the initial
	// and the running maximum.
	SaveInitial(ctx context.Context, gameID common.GameID, stats []PlayerInitialStats) error

	// UpdateMax updates the max fields for every user in stats by
	// per-component maximum. Existing aggregate entries below the new
	// observation are raised; existing entries at or above the new
	// observation are left unchanged. Calling UpdateMax for a user that
	// has no aggregate entry yet creates one whose initial fields and
	// max fields both equal the observation, so callers may safely call
	// UpdateMax without first calling SaveInitial.
	UpdateMax(ctx context.Context, gameID common.GameID, stats []PlayerObservedStats) error

	// Load returns the GameTurnStatsAggregate stored for gameID. The
	// aggregate is empty (Players length zero) when no observation has
	// been recorded yet; the GameID is always populated. The returned
	// Players slice is ordered by UserID ascending so capability
	// evaluation produces deterministic side-effect order on replay.
	Load(ctx context.Context, gameID common.GameID) (GameTurnStatsAggregate, error)

	// Delete removes every aggregate entry for gameID. The call is a
	// no-op when no entries exist; no error is returned in that case.
	Delete(ctx context.Context, gameID common.GameID) error
}