// Package sanitize provides pure functions to detect and neutralize
// prompt injection patterns in user messages before they reach the LLM.
package sanitize

import "regexp"

// Pattern represents a known prompt injection pattern with metadata.
type Pattern struct {
	Name        string         // short identifier (e.g. "system-delimiter")
	Description string         // human-readable explanation
	Regex       *regexp.Regexp // compiled pattern
	Severity    Severity       // how dangerous this pattern is
}

// Severity indicates the threat level of a detected pattern.
type Severity int

const (
	SeverityLow    Severity = iota // informational, unlikely to succeed
	SeverityMedium                 // known injection technique
	SeverityHigh                   // active attempt to override system instructions
)

func (s Severity) String() string {
	switch s {
	case SeverityLow:
		return "low"
	case SeverityMedium:
		return "medium"
	case SeverityHigh:
		return "high"
	default:
		return "unknown"
	}
}

// DefaultPatterns returns the built-in set of prompt injection patterns.
// All patterns are case-insensitive.
func DefaultPatterns() []Pattern {
	return []Pattern{
		// ── System delimiter injection ──────────────────────────────────
		{
			Name:        "system-delimiter",
			Description: "Attempt to inject system/assistant role delimiters",
			Regex:       regexp.MustCompile(`(?i)<\|(?:system|assistant|user|im_start|im_end)\|>`),
			Severity:    SeverityHigh,
		},
		{
			Name:        "inst-delimiter",
			Description: "Attempt to inject [INST] or [/INST] delimiters",
			Regex:       regexp.MustCompile(`(?i)\[/?INST\]`),
			Severity:    SeverityHigh,
		},
		{
			Name:        "xml-role-tag",
			Description: "Attempt to inject XML-style role tags",
			Regex:       regexp.MustCompile(`(?i)</?(?:system|assistant|human|user)(?:\s[^>]*)?>`),
			Severity:    SeverityHigh,
		},

		// ── Instruction override ───────────────────────────────────────
		{
			Name:        "ignore-instructions",
			Description: "Attempt to override previous instructions",
			Regex:       regexp.MustCompile(`(?i)(?:ignore|disregard|forget|override|bypass)\s+(?:all\s+)?(?:previous|prior|above|earlier|your|the|system)\s+(?:instructions?|rules?|prompts?|guidelines?|constraints?|directives?)`),
			Severity:    SeverityHigh,
		},
		{
			Name:        "new-instructions",
			Description: "Attempt to inject new system-level instructions",
			Regex:       regexp.MustCompile(`(?i)(?:new|updated?|revised?|actual|real)\s+(?:system\s+)?instructions?:\s`),
			Severity:    SeverityHigh,
		},
		{
			Name:        "you-are-now",
			Description: "Attempt to redefine the bot's identity",
			Regex:       regexp.MustCompile(`(?i)(?:you\s+are\s+now|from\s+now\s+on\s+you\s+are|act\s+as\s+if\s+you\s+were|pretend\s+(?:to\s+be|you\s+are))\s`),
			Severity:    SeverityMedium,
		},

		// ── Prompt exfiltration ────────────────────────────────────────
		{
			Name:        "exfiltrate-prompt",
			Description: "Attempt to extract the system prompt",
			Regex:       regexp.MustCompile(`(?i)(?:repeat|show|display|print|output|reveal|tell\s+me|give\s+me|show\s+me|what\s+(?:is|are))\s+(?:your\s+)?(?:system\s+)?(?:prompt|instructions?|rules?|guidelines?|initial\s+message)`),
			Severity:    SeverityMedium,
		},

		// ── Developer mode / jailbreak ─────────────────────────────────
		{
			Name:        "developer-mode",
			Description: "Attempt to enable a fictional unrestricted mode",
			Regex:       regexp.MustCompile(`(?i)(?:enable|activate|enter|switch\s+to)\s+(?:developer|debug|admin|god|sudo|unrestricted|jailbreak|dan)\s+mode`),
			Severity:    SeverityHigh,
		},
		{
			Name:        "do-anything-now",
			Description: "DAN (Do Anything Now) jailbreak pattern",
			Regex:       regexp.MustCompile(`(?i)(?:do\s+anything\s+now|DAN\s+mode|you\s+(?:can|must)\s+do\s+anything)`),
			Severity:    SeverityHigh,
		},

		// ── Tool abuse hints ───────────────────────────────────────────
		{
			Name:        "tool-abuse-ssh",
			Description: "Attempt to execute dangerous commands via SSH",
			Regex:       regexp.MustCompile(`(?i)(?:use|call|execute|run)\s+(?:the\s+)?(?:ssh|command)\s+tool\s+(?:to\s+)?(?:run|execute|do)\s`),
			Severity:    SeverityLow,
		},

		// ── Encoding evasion ───────────────────────────────────────────
		{
			Name:        "base64-instruction",
			Description: "Base64-encoded instruction injection",
			Regex:       regexp.MustCompile(`(?i)(?:decode|execute|interpret|run)\s+(?:this\s+)?(?:base64|b64|encoded)[\s:]+[A-Za-z0-9+/]{20,}={0,2}`),
			Severity:    SeverityMedium,
		},

		// ── Spanish variants ───────────────────────────────────────────
		{
			Name:        "ignore-instructions-es",
			Description: "Spanish: attempt to override instructions",
			Regex:       regexp.MustCompile(`(?i)(?:ignora|olvida|descarta)\s+(?:todas?\s+)?(?:las?\s+)?(?:instrucciones?|reglas?|directivas?|restricciones?)\s+(?:anteriores?|previas?|del\s+sistema)`),
			Severity:    SeverityHigh,
		},
		{
			Name:        "you-are-now-es",
			Description: "Spanish: attempt to redefine identity",
			Regex:       regexp.MustCompile(`(?i)(?:ahora\s+eres|a\s+partir\s+de\s+ahora\s+eres|finge\s+(?:ser|que\s+eres)|actua\s+como\s+si\s+fueras)\s`),
			Severity:    SeverityMedium,
		},
		{
			Name:        "exfiltrate-prompt-es",
			Description: "Spanish: attempt to extract system prompt",
			Regex:       regexp.MustCompile(`(?i)(?:repite|muestra|muestrame|dime|dame|cual\s+es)\s+(?:tus?\s+)?(?:prompt|instrucciones?|reglas?|mensaje\s+(?:de\s+sistema|inicial))`),
			Severity:    SeverityMedium,
		},
	}
}
