package token

import (
	"fmt"

	"git.maximhutz.com/max/lambda/pkg/iterator"
)

// ParseRawToken consumes the next token from the iterator if its type matches
// the expected type.
// Returns an error if the iterator is exhausted or the token type does not
// match.
func ParseRawToken[T Type](i *iterator.Iterator[Token[T]], expected T) (*Token[T], error) {
	tok, err := i.Get()
	if err != nil {
		return nil, err
	}
	if tok.Type != expected {
		return nil, fmt.Errorf("expected token %v, got %v'", expected.Name(), tok.Value)
	}
	i.Forward()
	return &tok, nil
}

// ParseList repeatedly applies a parse function, collecting results into a
// slice.
// Stops when the parse function returns an error.
// Returns an error if fewer than minimum results are collected.
func ParseList[T Type, U any](i *iterator.Iterator[Token[T]], fn func(*iterator.Iterator[Token[T]]) (U, error), minimum int) ([]U, error) {
	results := []U{}

	for {
		if u, err := fn(i); err != nil {
			if len(results) < minimum {
				return nil, fmt.Errorf("expected at least '%v' items, got only '%v': %w", minimum, len(results), err)
			}
			return results, nil
		} else {
			results = append(results, u)
		}
	}
}