package parser

import (
	"bytes"
	"strings"

	"go.arsenm.dev/amu/ast"
	"go.arsenm.dev/amu/scanner"
)

// parseImage attempts to parse an image
func (p *Parser) parseImage() *ast.Image {
	// Create new image
	img := &ast.Image{}

	// Create buffers for image properties
	altBuf := &bytes.Buffer{}
	srcBuf := &bytes.Buffer{}
	linkBuf := &bytes.Buffer{}
	// Set current buffer to alt text buffer
	currentBuf := altBuf

	// Scan token
	tok, lit := p.scan()
	// If token is not PUNCT or literal is not "["
	if tok != scanner.PUNCT || lit != "[" {
		// Return nil as this is not a valid image
		return nil
	}

	// Declare variable for last literal
	var lastLit string

parseLoop:
	for {
		// Scan token
		tok, lit := p.scan()

		switch tok {
		case scanner.WORD:
			// Write word to current buffer
			currentBuf.WriteString(lit)
		case scanner.WS:
			// Write whitespace to current buffer
			currentBuf.WriteString(lit)
		case scanner.PUNCT:
			// If last literal is "]" and current is "("
			if lastLit == "]" && lit == "(" {
				// Set current buffer to source buffer
				currentBuf = srcBuf
				// Continue to next token
				continue
			}
			// If last literal is ")" and current is "{"
			if lastLit == ")" && lit == "{" {
				// Set current buffer to link buffer
				currentBuf = linkBuf
				// Continue to next token
				continue
			}
			// If current literal is "}" and current buffer is link buffer
			if lit == "}" && currentBuf == linkBuf {
				// Stop parsing
				break parseLoop
			}

			// If literal does not contain any of the restrict characters
			if !strings.ContainsAny(lit, "()[]{}") {
				// Write literal to current buffer
				currentBuf.WriteString(lit)
			}
		case scanner.EOL, scanner.EOF:
			// Return nil as this is not a valid link
			return nil
		}
		// Set last literal
		lastLit = lit
	}

	// Set image properties
	img.Alternate = altBuf.String()
	img.Source = srcBuf.String()
	img.Link = linkBuf.String()

	return img
}