package logging

import (
	"encoding/base64"
	"fmt"
	"mime"
	"net/url"
	"regexp"
	"strconv"
	"strings"
)

// Inline attachments remain opaque in every log format, regardless of the
// carrier field or element. Only standard-decoded media type and byte count
// are projected; malformed declarations never restore their payload.
var inlineDataURI = regexp.MustCompile(`(?i)\bdata:[^,\s<>"']*,[^\s<>"']*`)

func redactInlineBinary(s string) string {
	if strings.HasPrefix(strings.ToLower(strings.TrimSpace(s)), "data:") {
		return inlineBinarySummary(strings.TrimSpace(s))
	}
	return inlineDataURI.ReplaceAllStringFunc(s, inlineBinarySummary)
}

// Repeated formatting must retain only our typed attachment projection.
func isInlineBinarySummary(s string) bool {
	if !strings.HasPrefix(s, "[BINARY ") || !strings.HasSuffix(s, "]") {
		return false
	}
	fields := strings.Fields(s[len("[BINARY ") : len(s)-1])
	if len(fields) != 2 && len(fields) != 3 {
		return false
	}
	if !strings.HasPrefix(fields[0], "type=") || !strings.HasPrefix(fields[1], "bytes=") {
		return false
	}
	kind := strings.TrimPrefix(fields[0], "type=")
	if kind != "unknown" {
		media, params, err := mime.ParseMediaType(kind)
		if err != nil || media != kind || !strings.Contains(media, "/") || len(params) != 0 {
			return false
		}
	}
	count := strings.TrimPrefix(fields[1], "bytes=")
	if count != "unknown" {
		if _, err := strconv.ParseUint(count, 10, 64); err != nil {
			return false
		}
	}
	return len(fields) == 2 || fields[2] == "error=invalid_data_uri"
}

func inlineBinarySummary(uri string) string {
	header, payload, ok := strings.Cut(uri[5:], ",")
	if !ok {
		return "[BINARY type=unknown bytes=unknown error=invalid_data_uri]"
	}
	encoded := strings.HasSuffix(strings.ToLower(header), ";base64")
	if encoded {
		header = header[:len(header)-7]
	}
	if header == "" {
		header = "text/plain;charset=US-ASCII"
	}
	media, _, err := mime.ParseMediaType(header)
	if err != nil || !strings.Contains(media, "/") {
		return "[BINARY type=unknown bytes=unknown error=invalid_data_uri]"
	}
	raw, err := url.PathUnescape(payload)
	if err != nil {
		return fmt.Sprintf("[BINARY type=%s bytes=unknown error=invalid_data_uri]", media)
	}
	data := []byte(raw)
	if encoded {
		data, err = base64.StdEncoding.DecodeString(raw)
		if err != nil {
			return fmt.Sprintf("[BINARY type=%s bytes=unknown error=invalid_data_uri]", media)
		}
	}
	return fmt.Sprintf("[BINARY type=%s bytes=%d]", media, len(data))
}