package proxy

import (
	"net/http"
	"strings"
)

// isRetriable reports whether an upstream status code should trigger failover
// to the next account before any bytes are streamed to the client.
//
// 429 — rate limit / usage limit (retryable cooldown)
// 402 — payment required; treated as retryable when the body text matches a
//
//	usage-window pattern ("usage limit", "limit reached", "exhausted",
//	"daily/weekly/monthly limit"). A bare "insufficient credits" is also
//	retriable (billing disable) — we still fail over, just with a longer
//	cooldown.
//
// 5xx — transient server error
// 408 — request timeout
// Other 4xx are not retriable: the request is malformed or the model is
// unknown, so retrying on another account would fail identically.
func isRetriable(status int) bool {
	switch {
	case status == http.StatusTooManyRequests:
		return true
	case status == http.StatusPaymentRequired:
		return true
	case status >= 500:
		return true
	case status == http.StatusRequestTimeout:
		return true
	default:
		return false
	}
}

// shouldCooldown reports whether an account should be marked cooldown after a
// retriable failure. 5xx does not trigger cooldown (the error may be
// transient and unrelated to this account's quota). 429 and 402 always do.
func shouldCooldown(status int, bodyPreview string) bool {
	switch {
	case status == http.StatusTooManyRequests:
		return true
	case status == http.StatusPaymentRequired:
		return true
	default:
		return false
	}
}

// isBillingDisable reports whether the error body indicates a billing/credit
// exhaustion (longer cooldown) rather than a transient usage-window limit.
// Used for logging/diagnostics; the cooldown duration is the same in v1.
func isBillingDisable(bodyPreview string) bool {
	low := strings.ToLower(bodyPreview)
	for _, marker := range []string{"insufficient credits", "credit balance", "billing"} {
		if strings.Contains(low, marker) {
			return true
		}
	}
	return false
}