package processor

import (
	"fmt"
	"time"

	"apskel-pos-be/internal/entities"
)

// ValidateResult checks a result against a game's result_rules (docs/rfc-enakgame.md
// §7.2 step 5) and returns why it is not believable, or nil when it is. A rule left
// out does not apply, so a game without result_rules accepts every result.
//
// A failed result is not an error: the session completes, earns nothing and is
// flagged, with these reasons in its reward_breakdown.
func ValidateResult(rules entities.GameResultRules, result SessionResult, startedAt, submittedAt time.Time) []string {
	var reasons []string
	elapsed := submittedAt.Sub(startedAt).Seconds()
	if rules.MinDurationSeconds != nil && elapsed < float64(*rules.MinDurationSeconds) {
		reasons = append(reasons, fmt.Sprintf("played %.0f seconds, under the minimum of %d", elapsed, *rules.MinDurationSeconds))
	}
	if result.Score != nil {
		score := *result.Score
		if score < 0 {
			reasons = append(reasons, "score cannot be negative")
		}
		if rules.MaxScore != nil && score > *rules.MaxScore {
			reasons = append(reasons, fmt.Sprintf("score %d is above the maximum of %d", score, *rules.MaxScore))
		}
		if rules.MaxScorePerSecond != nil && score > 0 {
			// A score with no time played at all is never believable.
			if elapsed <= 0 || float64(score)/elapsed > *rules.MaxScorePerSecond {
				reasons = append(reasons, fmt.Sprintf("score %d in %.0f seconds is above %g per second", score, elapsed, *rules.MaxScorePerSecond))
			}
		}
	}
	if result.Outcome != nil && len(rules.Outcomes) > 0 && !containsString(rules.Outcomes, *result.Outcome) {
		reasons = append(reasons, fmt.Sprintf("unknown outcome %q", *result.Outcome))
	}
	return reasons
}