package parser

import (
	"fmt"
	"path/filepath"

	"github.com/kashav/fsql/tokenizer"
)

// parseSourceList parses the list of directories passed to the FROM clause. If
// a source is followed by the AS keyword, the following word is registered as
// an alias.
func (p *parser) parseSourceList(sources *map[string][]string,
	aliases *map[string]string) error {
	for {
		// If the next token is a hypen, exclude this directory.
		sourceType := "include"
		if token := p.expect(tokenizer.Hyphen); token != nil {
			sourceType = "exclude"
		}

		source := p.expect(tokenizer.Identifier)
		if source == nil {
			return p.currentError()
		}
		source.Raw = filepath.Clean(source.Raw)
		(*sources)[sourceType] = append((*sources)[sourceType], source.Raw)

		if token := p.expect(tokenizer.As); token != nil {
			alias := p.expect(tokenizer.Identifier)
			if alias == nil {
				return p.currentError()
			}
			if sourceType == "exclude" {
				return fmt.Errorf("cannot alias excluded directory %s", source.Raw)
			}
			(*aliases)[alias.Raw] = source.Raw
		}

		if p.expect(tokenizer.Comma) == nil {
			break
		}
	}
	return nil
}