app/engine/stitch/__init__.py

"""Rebuild document text from processed blocks."""

from __future__ import annotations

from app.engine.models import DocumentBlock


def stitch_blocks(blocks: list[DocumentBlock]) -> str:
    """Join blocks preserving blank lines and non-rewriteable sections."""
    if not blocks:
        return ""
    parts: list[str] = []
    for i, block in enumerate(blocks):
        if block.kind == "blank":
            # Represented as paragraph separator; avoid stacking too many
            if parts and not parts[-1].endswith("\n\n"):
                if parts[-1] and not parts[-1].endswith("\n"):
                    parts.append("\n\n")
                elif parts[-1].endswith("\n") and not parts[-1].endswith("\n\n"):
                    parts.append("\n")
            continue
        text = block.text or ""
        if i > 0 and parts and not parts[-1].endswith("\n"):
            # Separate consecutive non-blank blocks with blank line if both are paras/headings
            prev = blocks[i - 1]
            if prev.kind != "blank":
                parts.append("\n\n")
        parts.append(text)
    out = "".join(parts)
    out = out.replace("\n\n\n\n", "\n\n").strip()
    return out


def join_sentences(sentences: list[str]) -> str:
    return " ".join(s.strip() for s in sentences if s and s.strip())