import json
from pathlib import Path


def parse_text(path):
    text = path.read_text(encoding="utf-8", errors="replace")
    return path.stem, text, {}


def parse_markdown(path):
    text = path.read_text(encoding="utf-8", errors="replace")
    title = path.stem
    for line in text.split("\n"):
        if line.startswith("# "):
            title = line.lstrip("#").strip()
            break
    return title, text, {}


def parse_pdf(path):
    from pypdf import PdfReader
    reader = PdfReader(str(path))
    pages = [p.extract_text() or "" for p in reader.pages]
    text = "\n\n".join(pages)
    title = path.stem
    if reader.metadata and reader.metadata.title:
        title = reader.metadata.title
    return title, text, {"page_count": len(pages)}


def parse_claude_export(path):
    data = json.loads(path.read_text(encoding="utf-8", errors="replace"))
    
    if isinstance(data, dict) and ("name" in data or "title" in data):
        return _format_conversation(data, path.stem)
    elif isinstance(data, list):
        all_text = []
        for conv in data:
            _, text, _ = _format_conversation(conv, "")
            all_text.append(text)
        return path.stem, "\n\n---\n\n".join(all_text), {"conversation_count": len(data)}
    else:
        return path.stem, json.dumps(data, indent=2), {}


def _format_conversation(conv, default_title):
    title = conv.get("name") or conv.get("title") or default_title
    messages = conv.get("messages", []) or conv.get("chat_messages", [])
    
    parts = [f"# {title}\n"]
    for msg in messages:
        role_raw = msg.get("role") or msg.get("sender") or "unknown"
        # Normalize to USER/ASSISTANT for consistency with OpenClaw transcripts
        role = "USER" if role_raw == "human" else ("ASSISTANT" if role_raw == "assistant" else role_raw.upper())
        content = msg.get("content") or msg.get("text") or ""
        if isinstance(content, list):
            content = "\n".join(
                block.get("text", "") for block in content 
                if isinstance(block, dict) and block.get("type") == "text"
            )
        if not content.strip():
            continue  # skip empty blocks (tool_use, tool_result, etc.)
        parts.append(f"\n**{role}**:\n\n{content}\n")
    
    return title, "\n".join(parts), {
        "message_count": len(messages),
        "format": "claude_export",
    }


PARSERS = {
    ".txt": parse_text,
    ".md": parse_markdown,
    ".markdown": parse_markdown,
    ".pdf": parse_pdf,
    ".json": parse_claude_export,
}


def parse_file(path):
    suffix = path.suffix.lower()
    parser = PARSERS.get(suffix)
    if not parser:
        raise ValueError(f"No parser for {suffix}")
    return parser(path)