#!/usr/bin/env python3
"""Render a document from a JSON spec on stdin to a .docx file.

Replaces pandoc for this path. Pandoc reads markdown, so everything had to be
flattened to markdown first — and a deck flattened to markdown loses what made
it a deck: a comparison became two headings and two lists, a callout became bold
text, a figure became nothing at all. Coming from the typed spec, a comparison
is a two-column table, a callout is a shaded box, and a figure keeps its caption.

Input (stdin, JSON):
  {"title": str, "subtitle": str, "date": str, "blocks": [ ... ]}

Blocks:
  {"type":"heading","level":1..4,"text":str}
  {"type":"para","text":str,"muted":bool}
  {"type":"bullets","items":[{"text":str,"level":0..4}]}
  {"type":"table","header":[str],"rows":[[str]]}
  {"type":"callout","text":str}
  {"type":"image","path":str,"caption":str}

Output: argv[1]. Errors to stderr, non-zero exit, so the caller can fall back.
"""
import json
import os
import re
import sys

from docx import Document
from docx.enum.table import WD_TABLE_ALIGNMENT
from docx.enum.text import WD_ALIGN_PARAGRAPH
from docx.oxml import OxmlElement
from docx.oxml.ns import qn
from docx.shared import Emu, Pt, RGBColor

try:
    from PIL import Image
except Exception:  # pragma: no cover
    Image = None

INK = RGBColor(0x1F, 0x29, 0x37)
MUTED = RGBColor(0x4B, 0x55, 0x63)
ACCENT = RGBColor(0x25, 0x63, 0xEB)
CALLOUT_INK = RGBColor(0x78, 0x35, 0x0F)

BODY_FONT = "Calibri"
CONTENT_WIDTH_EMU = Emu(5486400)   # 6" — A4/Letter with 1" margins


def shade(element, hex_fill):
    """Cell or paragraph shading. python-docx exposes no API for either."""
    shd = OxmlElement("w:shd")
    shd.set(qn("w:val"), "clear")
    shd.set(qn("w:color"), "auto")
    shd.set(qn("w:fill"), hex_fill)
    element.append(shd)


def style_body(document):
    normal = document.styles["Normal"]
    normal.font.name = BODY_FONT
    normal.font.size = Pt(11)
    normal.font.color.rgb = INK
    normal.paragraph_format.space_after = Pt(8)
    normal.paragraph_format.line_spacing = 1.15


def add_runs(paragraph, text, bold=False, color=None, size=None):
    """Inline **bold** and *italic* survive; everything else is literal."""
    for chunk, is_bold, is_italic in split_inline(text):
        run = paragraph.add_run(chunk)
        run.bold = bold or is_bold
        run.italic = is_italic
        run.font.name = BODY_FONT
        if color is not None:
            run.font.color.rgb = color
        if size is not None:
            run.font.size = Pt(size)


def split_inline(text):
    out = []
    pattern = re.compile(r"(\*\*|__)(.+?)\1|(\*|_)(.+?)\3")
    index = 0
    for match in pattern.finditer(text or ""):
        if match.start() > index:
            out.append((text[index:match.start()], False, False))
        if match.group(2) is not None:
            out.append((match.group(2), True, False))
        else:
            out.append((match.group(4), False, True))
        index = match.end()
    if index < len(text or ""):
        out.append((text[index:], False, False))
    return out or [(text or "", False, False)]


def heading(document, spec):
    level = max(1, min(int(spec.get("level") or 2), 4))
    para = document.add_paragraph()
    para.paragraph_format.space_before = Pt(16 if level <= 2 else 12)
    para.paragraph_format.space_after = Pt(6)
    para.paragraph_format.keep_with_next = True
    sizes = {1: 18, 2: 14, 3: 12, 4: 11}
    add_runs(para, spec.get("text") or "", bold=True,
             color=ACCENT if level == 1 else INK, size=sizes[level])


def para(document, spec):
    p = document.add_paragraph()
    add_runs(p, spec.get("text") or "", color=MUTED if spec.get("muted") else None,
             size=10 if spec.get("muted") else None)
    if spec.get("muted"):
        p.paragraph_format.left_indent = Emu(228600)


def bullets(document, spec):
    for item in spec.get("items") or []:
        text = (item.get("text") or "").strip()
        if not text:
            continue
        level = max(0, min(int(item.get("level") or 0), 4))
        p = document.add_paragraph(style="List Bullet" if level == 0 else "List Bullet 2")
        p.paragraph_format.left_indent = Emu(228600 * (level + 1))
        p.paragraph_format.space_after = Pt(4)
        add_runs(p, text)


def table(document, spec):
    header = spec.get("header") or []
    rows = spec.get("rows") or []
    if not rows:
        return
    cols = max(len(header), max((len(r) for r in rows), default=1))
    t = document.add_table(rows=len(rows) + (1 if header else 0), cols=cols)
    t.style = "Table Grid"
    t.alignment = WD_TABLE_ALIGNMENT.CENTER
    offset = 0
    if header:
        for c in range(cols):
            cell = t.cell(0, c)
            cell.text = ""
            add_runs(cell.paragraphs[0], header[c] if c < len(header) else "", bold=True, size=10)
            shade(cell._tc.get_or_add_tcPr(), "E7EEFC")
        offset = 1
    for r, row in enumerate(rows):
        for c in range(cols):
            cell = t.cell(r + offset, c)
            cell.text = ""
            add_runs(cell.paragraphs[0], row[c] if c < len(row) else "", size=10)
    document.add_paragraph().paragraph_format.space_after = Pt(4)


def callout(document, spec):
    """One thing worth stopping on, in a shaded box with a rule down its side."""
    t = document.add_table(rows=1, cols=1)
    t.alignment = WD_TABLE_ALIGNMENT.CENTER
    cell = t.cell(0, 0)
    cell.text = ""
    shade(cell._tc.get_or_add_tcPr(), "FEF3C7")
    add_runs(cell.paragraphs[0], spec.get("text") or "", bold=True, color=CALLOUT_INK)
    document.add_paragraph().paragraph_format.space_after = Pt(4)


def image(document, spec):
    path = spec.get("path")
    if not path or not os.path.exists(path):
        return
    width = CONTENT_WIDTH_EMU
    if Image is not None:
        try:
            with Image.open(path) as img:
                # A tall figure at full width runs off the page; cap the height
                # and let the width follow rather than stretching either.
                if img.width and img.height and (img.height / img.width) > 1.1:
                    width = Emu(int(CONTENT_WIDTH_EMU * 0.62))
        except Exception:
            pass
    document.add_picture(path, width=width)
    document.paragraphs[-1].alignment = WD_ALIGN_PARAGRAPH.CENTER
    caption = (spec.get("caption") or "").strip()
    if caption:
        p = document.add_paragraph()
        p.alignment = WD_ALIGN_PARAGRAPH.CENTER
        add_runs(p, caption, color=MUTED, size=9)
        p.runs[0].italic = True


BUILDERS = {
    "heading": heading, "para": para, "bullets": bullets,
    "table": table, "callout": callout, "image": image,
}


def main():
    if len(sys.argv) < 2:
        print("usage: render_docx.py <output.docx>  (spec on stdin)", file=sys.stderr)
        return 2
    spec = json.load(sys.stdin)
    blocks = spec.get("blocks") or []
    if not blocks:
        print("spec contains no blocks", file=sys.stderr)
        return 3

    document = Document()
    style_body(document)

    title = document.add_paragraph()
    title.paragraph_format.space_after = Pt(2)
    add_runs(title, spec.get("title") or "Resource", bold=True, size=24)
    for line in [spec.get("subtitle"), spec.get("date")]:
        if not line:
            continue
        sub = document.add_paragraph()
        sub.paragraph_format.space_after = Pt(0)
        add_runs(sub, line, color=MUTED, size=11)
    document.add_paragraph()

    for block in blocks:
        BUILDERS.get(block.get("type") or "para", para)(document, block)

    document.save(sys.argv[1])
    return 0


if __name__ == "__main__":
    sys.exit(main())