package parser

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

// parseList attempts to parse a list
func (p *Parser) parseList() *ast.List {
	// Create new list
	list := &ast.List{}

	tok, lit := p.scan()

	// If token is not WORD or literal is not "=list"
	if tok != scanner.WORD || lit != "=list" {
		// Return nil as this list is invalid
		return nil
	}

	tok, lit = p.scan()

	// If token is not PUNCT or literal is not "["
	if tok != scanner.PUNCT || lit != "[" {
		// Return nil as this list is invalid
		return nil
	}

	tok, lit = p.scan()

	// If token is not WORD (the name of the function)
	if tok != scanner.WORD {
		// Return nil as this list is invalid
		return nil
	}

	list.Type = lit

	tok, lit = p.scan()

	// If token is not PUNCT or literal is not "]"
	if tok != scanner.PUNCT || lit != "]" {
		// Return nil as this list is invalid
		return nil
	}

parseLoop:
	for {
		// If end of file
		if tok == scanner.EOF {
			// Return whatever was parsed so far
			return list
		}

		// Create new list item at level 0
		item := ast.ListItem{Level: 0}

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

			// If end of file
			if tok == scanner.EOF {
				// Return whatever was parsed so far
				return list
			}

			// If token is not punctuation or literal is not "."
			if tok != scanner.PUNCT || lit != "." {
				// Break out of loop as this is the end of level
				break
			}

			// Increment item level
			item.Level++
		}

		for tok != scanner.PUNCT && lit != "." {
			// If token is WORD and literal is "=end"
			if tok == scanner.WORD && lit == "=end" {
				// Scan token
				tok, lit = p.scan()
				// If token is not PUNCT and literal is not "["
				if tok != scanner.PUNCT && lit != "[" {
					// Return nil as this is not a valid list
					return nil
				}
				// Scan token
				tok, lit = p.scan()
				// If token is not PUNCT and literal is not "]"
				if tok != scanner.PUNCT && lit != "]" {
					// Return nil as this is not a valid list
					return nil
				}
				// Add item to list
				list.Items = append(list.Items, item)
				// Stop parsing
				break parseLoop
			}

			// If end of file
			if tok == scanner.EOF {
				// Return whatever was parsed so far
				return list
			}

			// Unscan character as it will be required for para
			p.unscan()
			// Attempt to parse para until one newline encountered
			para := p.parsePara(1)
			if para == nil {
				break
			}
			// Add para to item content
			item.Content = append(item.Content, para)

			// Scan token for next loop
			tok, lit = p.scan()

			// if end of line
			if tok == scanner.EOL {
				// Scan again
				tok, lit = p.scan()
			}
		}

		// If token is part of level
		if tok == scanner.PUNCT && lit == "." {
			// Unscan for next level loop
			p.unscan()
		}

		// If no content in item
		if len(item.Content) == 0 {
			// Continue to next item
			continue
		}

		// Add item to list items
		list.Items = append(list.Items, item)
	}

	// Return lists
	return list
}