"""Generate simple expressive faces for the mask (16 rows tall).

The display is ~48x16 on the units we measured. Faces are drawn into a column
list (``width`` columns, each 16 ints, row 0 = top) compatible with
``bitmap.encode_bitmap``. Color is per-column, so a face is most reliable in a
single color (eyes and mouth can share columns).

``mouth`` 0..4 = closed..wide-open; ``eyes`` True/False = open/blink;
``look`` shifts the eyes left(-)/right(+).
"""

from __future__ import annotations

from typing import List

from constants import MASK_HEIGHT

DISPLAY_WIDTH = 48  # measured on a MASK-05xxxx unit


def _blank(width: int) -> List[List[int]]:
    return [[0] * width for _ in range(MASK_HEIGHT)]


def _fill(rows, r0, r1, c0, c1, width):
    for r in range(max(0, r0), min(MASK_HEIGHT, r1 + 1)):
        for c in range(max(0, c0), min(width, c1 + 1)):
            rows[r][c] = 1


def face(mouth: int = 0, eyes: bool = True, look: int = 0,
         width: int = DISPLAY_WIDTH) -> List[List[int]]:
    """Build a face and return it as columns (width x 16)."""
    rows = _blank(width)
    cx = width // 2
    quarter = width // 4

    # --- eyes ---
    eye_hw = 3          # half-width
    lx, rx = cx - quarter, cx + quarter
    if eyes:
        _fill(rows, 3, 7, lx - eye_hw + look, lx + eye_hw + look, width)
        _fill(rows, 3, 7, rx - eye_hw + look, rx + eye_hw + look, width)
    else:  # blink: a thin closed line
        _fill(rows, 6, 6, lx - eye_hw, lx + eye_hw, width)
        _fill(rows, 6, 6, rx - eye_hw, rx + eye_hw, width)

    # --- mouth ---
    m = max(0, min(4, mouth))
    if m == 0:  # closed: a small smile line
        _fill(rows, 12, 12, cx - 7, cx + 7, width)
    else:
        top, bot = 12 - m, 11 + m
        hw = 8 - (m - 1)         # narrows as it opens, for an "O" shape
        _fill(rows, top, bot, cx - hw, cx + hw, width)

    return [[rows[r][c] for r in range(MASK_HEIGHT)] for c in range(width)]


# Convenience named expressions -> (mouth, eyes, look)
EXPRESSIONS = {
    "neutral": dict(mouth=0, eyes=True),
    "blink": dict(mouth=0, eyes=False),
    "talk_small": dict(mouth=1, eyes=True),
    "talk_mid": dict(mouth=2, eyes=True),
    "talk_open": dict(mouth=3, eyes=True),
    "talk_wide": dict(mouth=4, eyes=True),
    "look_left": dict(mouth=0, eyes=True, look=-3),
    "look_right": dict(mouth=0, eyes=True, look=3),
}


def expression(name: str, width: int = DISPLAY_WIDTH) -> List[List[int]]:
    return face(width=width, **EXPRESSIONS[name])


def ascii_preview(columns) -> str:
    """Render columns as ASCII art (for offline checks)."""
    width = len(columns)
    return "\n".join(
        "".join("#" if columns[c][r] else " " for c in range(width))
        for r in range(MASK_HEIGHT)
    )