import time
from netlib.exceptions import TcpDisconnect

BLOCKSIZE = 1024
# It's not clear what the upper limit for time.sleep is. It's lower than the
# maximum int or float. 1 year should do.
FOREVER = 60 * 60 * 24 * 365


def send_chunk(fp, val, blocksize, start, end):
    """
        (start, end): Inclusive lower bound, exclusive upper bound.
    """
    for i in range(start, end, blocksize):
        fp.write(
            val[i:min(i + blocksize, end)]
        )
    return end - start


def write_values(fp, vals, actions, sofar=0, blocksize=BLOCKSIZE):
    """
        vals: A list of values, which may be strings or Value objects.

        actions: A list of (offset, action, arg) tuples. Action may be "inject",
        "pause" or "disconnect".

        Both vals and actions are in reverse order, with the first items last.

        Return True if connection should disconnect.
    """
    sofar = 0
    try:
        while vals:
            v = vals.pop()
            offset = 0
            while actions and actions[-1][0] < (sofar + len(v)):
                a = actions.pop()
                offset += send_chunk(
                    fp,
                    v,
                    blocksize,
                    offset,
                    a[0] - sofar - offset
                )
                if a[1] == "pause":
                    time.sleep(
                        FOREVER if a[2] == "f" else a[2]
                    )
                elif a[1] == "disconnect":
                    return True
                elif a[1] == "inject":
                    send_chunk(fp, a[2], blocksize, 0, len(a[2]))
            send_chunk(fp, v, blocksize, offset, len(v))
            sofar += len(v)
        # Remainders
        while actions:
            a = actions.pop()
            if a[1] == "pause":
                time.sleep(a[2])
            elif a[1] == "disconnect":
                return True
            elif a[1] == "inject":
                send_chunk(fp, a[2], blocksize, 0, len(a[2]))
    except TcpDisconnect:  # pragma: no cover
        return True