package trace

import (
	"regexp"
	"strings"
)

// Redaction for everything the flow graph publishes (design/19 §3 红线: 不泄露敏感 ——
// 工具参数/内容脱敏；design/11 密钥不落日志). The graph is relayed to the admin panel
// and every connected client, so every string that reaches it — span props and
// span log events alike — is scrubbed and truncated here. Deciding to redact at
// publish time (rather than only at record time) means a runtime that records a
// raw tool result still cannot leak it.

// redactedMarker replaces anything that looks like a credential.
const redactedMarker = "[redacted]"

// secretPatterns match credential shapes that must never reach the dashboard: an
// API-key style assignment (plain or JSON), a standalone provider key, a bearer
// token, and a JWT. They are deliberately shallow (shape, not semantics): a false
// positive only over-redacts a dashboard string, while a false negative publishes a
// live credential.
var secretPatterns = []*regexp.Regexp{
	regexp.MustCompile(`(?i)\b[a-z0-9_]*(?:api[_-]?key|access[_-]?token|token|secret|password|passwd|pwd)[a-z0-9_]*"?\s*[:=]\s*"?[^\s"',;}\]]{6,}`),
	regexp.MustCompile(`\bsk-[A-Za-z0-9_\-]{8,}`),
	regexp.MustCompile(`(?i)\bbearer\s+[A-Za-z0-9_\-\.=]{10,}`),
	regexp.MustCompile(`\beyJ[A-Za-z0-9_\-]+\.[A-Za-z0-9_\-]+\.[A-Za-z0-9_\-]+`),
}

// secretKeyNames are prop names whose value is a credential whatever its shape, so
// a structured payload that names its secret ({api_key: "..."}) is redacted even
// when the value itself looks like ordinary text. Keys are compared after
// lower-casing and normalizing -/. to _.
var secretKeyNames = map[string]bool{
	"api_key": true, "apikey": true, "api_token": true, "access_token": true,
	"auth_token": true, "authorization": true, "token": true, "secret": true,
	"client_secret": true, "password": true, "passwd": true, "pwd": true,
	"credential": true, "credentials": true, "private_key": true, "session_key": true,
	"raw_api_key": true, "x_api_key": true, "bearer": true,
}

// secretKeySuffixes catch prefixed variants such as openai_api_key.
var secretKeySuffixes = []string{"_api_key", "_access_token", "_auth_token", "_secret", "_token"}

// IsSecretKey 报告某个 map 键是否命名了一个凭据。它是「密钥类键」的唯一判据：
// 出图前的清洗与参数摘要的生产者（loop/spanlog.go，裁决 11.4.3「密钥类参数
// 一律不显示值」）共用它，因此生产侧与最后一道防线不可能判得不一致。
func IsSecretKey(key string) bool {
	k := strings.NewReplacer("-", "_", ".", "_").Replace(strings.ToLower(strings.TrimSpace(key)))
	if secretKeyNames[k] {
		return true
	}
	for _, suffix := range secretKeySuffixes {
		if strings.HasSuffix(k, suffix) {
			return true
		}
	}
	return false
}

// RedactText scrubs credential-looking substrings from s and truncates the result
// to maxSummaryRunes, so a published string can never carry a secret or an
// unbounded blob.
func RedactText(s string) string {
	return RedactTextLimited(s, maxSummaryRunes)
}

// RedactTextLimited 是 RedactText 的**带上限**形态：同一套凭据形状清洗，截断长度
// 由调用方给。它存在的理由是两个读面要的不是同一种东西 ——
//
//   - **出图 / 摘要面**（span props、事件正文、工具结果摘要）要的是摘要 ⇒
//     `maxSummaryRunes`（80）足够，且保证一屏可读。这些调用方继续用 `RedactText`；
//   - **日志面**（`GET /admin/observability/logs` 的一行）要的是**可排障的全文** ⇒
//     80 会把长错误行拦腰截断，等于丢掉诊断信息。
//
// 但它绝不接受「无上限散用」：一条日志可能是 `%v` 出来的 MiB 级对象，原样塞进
// JSON 响应会撑爆面板的帧与响应体。因此上限**必须由调用方显式给出**并写清理由
// （网关侧见 `maxLogMsgRunes`）。
//
// limit <= 0 表示**不截断**（只打码），留给「体积已由自己界定」的调用方。
//
// 🔴 清洗逻辑仍然只有一份（redactSecrets）：上限是参数，不是第二条脱敏路径 ——
// 另写一套必然漂移，而漂移的方向总是「其中一面开始原样吐凭据」。
func RedactTextLimited(s string, limit int) string {
	return truncate(redactSecrets(s), limit)
}

// RedactEvent returns ev with every string value — including those nested in maps
// and slices, and including any value under a credential-named key — scrubbed and
// truncated. Timestamps, types and non-string scalars pass through unchanged.
func RedactEvent(ev Event) Event {
	out := Event{Time: ev.Time, Type: ev.Type}
	if ev.Props == nil {
		return out
	}
	out.Props = redactProps(ev.Props)
	return out
}

// redactProps scrubs a property map, applying the key-name rule at the top level
// as well as the shape rule to each value.
func redactProps(props map[string]any) map[string]any {
	out := make(map[string]any, len(props))
	for k, v := range props {
		if IsSecretKey(k) {
			out[k] = redactedMarker
			continue
		}
		out[k] = redactValue(v)
	}
	return out
}

// redactEvents returns a redacted copy of events for publication. A nil or empty
// slice yields nil so a node carries no empty log array.
func redactEvents(events []Event) []Event {
	if len(events) == 0 {
		return nil
	}
	out := make([]Event, len(events))
	for i, ev := range events {
		out[i] = RedactEvent(ev)
	}
	return out
}

// redactSecrets replaces every credential-shaped substring with the marker.
func redactSecrets(s string) string {
	if s == "" {
		return s
	}
	for _, re := range secretPatterns {
		s = re.ReplaceAllString(s, redactedMarker)
	}
	return s
}

// redactValue scrubs one prop/event value: a string is redacted and truncated, a
// map or slice is copied and redacted recursively (with credential-named keys
// replaced outright), and any other value (number, bool, time) passes through
// unchanged.
func redactValue(v any) any {
	switch x := v.(type) {
	case string:
		return RedactText(x)
	case map[string]any:
		return redactProps(x)
	case []any:
		out := make([]any, len(x))
		for i, item := range x {
			out[i] = redactValue(item)
		}
		return out
	case []string:
		out := make([]any, len(x))
		for i, item := range x {
			out[i] = RedactText(item)
		}
		return out
	case map[string]string:
		// 参数摘要以 map[string]string 生产时也必须逐键清洗，
		// 否则密钥会绕过键名规则原样出图（裁决 11.4.3 红线）。
		out := make(map[string]any, len(x))
		for k, v := range x {
			if IsSecretKey(k) {
				out[k] = redactedMarker
				continue
			}
			out[k] = RedactText(v)
		}
		return out
	default:
		return v
	}
}