package parse

import (
	"bytes"
	"strings"
)

// ImageRef represents an image referenced by a filter via OSC 9 marker.
type ImageRef struct {
	Index int    // Sequential position in the message; set by ExtractImages, not ParseImageOSC
	Path  string // Absolute path to image file on disk
	Alt   string // Alt text fallback
}

var oscImagePrefix = []byte("\033]9;image:")

// ParseImageOSC parses an OSC 9 image marker from a byte slice.
// Format: \033]9;image:path=/tmp/foo.png;alt=text\007
// The marker may appear anywhere in the line.
// Returns the parsed reference and whether parsing succeeded.
func ParseImageOSC(line []byte) (*ImageRef, bool) {
	start := bytes.Index(line, oscImagePrefix)
	if start == -1 {
		return nil, false
	}
	rest := line[start+len(oscImagePrefix):]

	// Find string terminator: BEL (\007) or ST (ESC \)
	end := -1
	for i := 0; i < len(rest); i++ {
		if rest[i] == '\007' {
			end = i
			break
		}
		if rest[i] == '\033' && i+1 < len(rest) && rest[i+1] == '\\' {
			end = i
			break
		}
	}
	if end == -1 {
		return nil, false
	}

	params := string(rest[:end])
	ref := &ImageRef{}
	for _, pair := range strings.Split(params, ";") {
		k, v, ok := strings.Cut(pair, "=")
		if !ok {
			continue
		}
		switch k {
		case "path":
			ref.Path = v
		case "alt":
			ref.Alt = v
		}
	}
	if ref.Path == "" {
		return nil, false
	}
	return ref, true
}