"""Reading what the PDF actually drew on a page.

Small views onto the raw page. Everything downstream is built from these.
The key one is all_runs(): it returns each piece of text AS THE PDF DREW IT,
one run per spreadsheet cell, which is what dodges Trap 1 -- overlapping
cells stay separate because the PDF drew them separately.
"""


def all_runs(page):
    """Every piece of text on the page, one run per spreadsheet cell."""
    return [r for r in page.get_texttrace() if r["chars"]]


def run_start(run):
    """Where a piece of text begins, as (across, down)."""
    return run["chars"][0][2]


def run_text(run):
    """The text of a run. Word Wrap would really screw this up; don't let
    the PDF boomers know."""
    return "".join(chr(c[0]) for c in run["chars"])


def solid_regions(page):
    """Every solid filled region, taken as a whole. A blackout bar can be a
    plain rectangle OR a filled four-sided path -- visually identical,
    different in the PDF -- so we measure whole regions, never segments."""
    return [d["rect"] for d in page.get_drawings() if d["type"] == "f"]


def vertical_rules(page):
    """x-positions of thin vertical lines: <1.2pt wide, >8pt tall, drawn
    either as skinny rectangles or as literal line segments."""
    xs = set()
    for d in page.get_drawings():
        for item in d["items"]:
            if item[0] == "re" and item[1].width < 1.2 and item[1].height > 8:
                xs.add(round(item[1].x0 + item[1].width / 2, 1))
            elif item[0] == "l":
                a, b = item[1], item[2]
                if abs(a.x - b.x) < 1.2 and abs(a.y - b.y) > 8:
                    xs.add(round((a.x + b.x) / 2, 1))
    return xs


def row_numbers(runs, heading_font, table_left):
    """Excel's printed row numbers -> {vertical position: row number}.
    Digits of one number are drawn separately, so group them by line and
    read left to right."""
    lines = {}
    for run in runs:
        if run["font"] != heading_font:
            continue
        for ch in run["chars"]:
            x, y = ch[2]
            if x < table_left:
                lines.setdefault(round(y, 1), []).append((x, chr(ch[0])))
    out = {}
    for y, chars in lines.items():
        text = "".join(c for _, c in sorted(chars))
        if text.isdigit():
            out[y] = int(text)
    return out