import typing as t

# The generic time format is based on python time.strftime.
# https://docs.python.org/3/library/time.html#time.strftime
from sqlglot.trie import TrieResult, in_trie, new_trie


def format_time(
    string: str, mapping: t.Dict[str, str], trie: t.Optional[t.Dict] = None
) -> t.Optional[str]:
    """
    Converts a time string given a mapping.

    Examples:
        >>> format_time("%Y", {"%Y": "YYYY"})
        'YYYY'

        Args:
            mapping: dictionary of time format to target time format.
            trie: optional trie, can be passed in for performance.

        Returns:
            The converted time string.
    """
    if not string:
        return None

    start = 0
    end = 1
    size = len(string)
    trie = trie or new_trie(mapping)
    current = trie
    chunks = []
    sym = None

    while end <= size:
        chars = string[start:end]
        result, current = in_trie(current, chars[-1])

        if result == TrieResult.FAILED:
            if sym:
                end -= 1
                chars = sym
                sym = None
            start += len(chars)
            chunks.append(chars)
            current = trie
        elif result == TrieResult.EXISTS:
            sym = chars

        end += 1

        if result != TrieResult.FAILED and end > size:
            chunks.append(chars)

    return "".join(mapping.get(chars, chars) for chars in chunks)
