// Package privacy provides PII detection for narratives and annotations.
package privacy

import (
	"regexp"
)

// piiPatterns contains regex patterns for detecting PII.
var piiPatterns = map[string]*regexp.Regexp{
	"email":       regexp.MustCompile(`\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b`),
	"ssn":         regexp.MustCompile(`\b\d{3}-\d{2}-\d{4}\b`),
	"phone":       regexp.MustCompile(`\b\d{3}-\d{3}-\d{4}\b`),
	"credit_card": regexp.MustCompile(`\b(?:\d[ -]*?){13,16}\b`),
	"ip_address":  regexp.MustCompile(`\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b`),
}

// PIIFinding represents a detected PII instance.
type PIIFinding struct {
	Type     string `json:"type"`
	Sample   string `json:"sample"`
	Position int    `json:"position"`
	Length   int    `json:"length"`
}

// DetectPII scans text for potential PII.
func DetectPII(text string) []PIIFinding {
	var findings []PIIFinding

	for piiType, pattern := range piiPatterns {
		matches := pattern.FindAllStringIndex(text, -1)
		for _, match := range matches {
			findings = append(findings, PIIFinding{
				Type:     piiType,
				Position: match[0],
				Length:   match[1] - match[0],
				Sample:   RedactSample(text[match[0]:match[1]]),
			})
		}
	}

	return findings
}

// HasPII returns true if text contains PII.
func HasPII(text string) bool {
	return len(DetectPII(text)) > 0
}

// RedactSample creates a safe sample for reporting.
func RedactSample(match string) string {
	if len(match) <= 4 {
		return "[PII]"
	}
	return match[:2] + "..." + match[len(match)-2:]
}