"""
Export module for notes.qpid.pro — Stage 2
Supports: CSV (Excel-friendly with BOM), JSON, Anki TSV (Cloze-ready), Markdown.
"""
import csv
import io
import json
import re
from datetime import datetime, timezone
from typing import List, Dict, Any


def export_csv(cards: List[Dict[str, Any]]) -> bytes:
    """CSV with UTF-8 BOM for correct Excel auto-detection of encoding."""
    output = io.StringIO()
    fieldnames = [
        "term", "translation", "context", "phonetic",
        "part_of_speech", "definition_en", "collection", "tags", "notes", "created_at",
    ]
    writer = csv.DictWriter(
        output,
        fieldnames=fieldnames,
        extrasaction="ignore",
        quoting=csv.QUOTE_MINIMAL,
        lineterminator="\r\n",
    )
    writer.writeheader()
    for c in cards:
        writer.writerow({
            "term": c.get("term") or "",
            "translation": c.get("translation") or "",
            "context": c.get("context_sentence") or c.get("context") or "",
            "phonetic": c.get("phonetic") or "",
            "part_of_speech": c.get("part_of_speech") or "",
            "definition_en": c.get("definition_en") or "",
            "collection": c.get("collection") or "General",
            "tags": c.get("tags") or "",
            "notes": c.get("notes") or "",
            "created_at": c.get("created_at") or "",
        })
    # UTF-8 BOM (\ufeff) so Excel auto-detects encoding
    return ("\ufeff" + output.getvalue()).encode("utf-8")


def export_json(cards: List[Dict[str, Any]]) -> bytes:
    """Full JSON export with metadata header."""
    payload = {
        "exported_at": datetime.now(timezone.utc).isoformat(),
        "total": len(cards),
        "cards": [
            {
                "id": c.get("id"),
                "term": c.get("term") or "",
                "translation": c.get("translation") or "",
                "context_sentence": c.get("context_sentence") or c.get("context") or "",
                "phonetic": c.get("phonetic") or "",
                "part_of_speech": c.get("part_of_speech") or "",
                "definition_en": c.get("definition_en") or "",
                "collection": c.get("collection") or "General",
                "tags": c.get("tags") or "",
                "notes": c.get("notes") or "",
                "audio_url": c.get("audio_url") or "",
                "created_at": c.get("created_at") or "",
                "updated_at": c.get("updated_at") or "",
            }
            for c in cards
        ],
    }
    return json.dumps(payload, ensure_ascii=False, indent=2).encode("utf-8")


def export_anki_tsv(cards: List[Dict[str, Any]]) -> bytes:
    """
    Anki-compatible tab-separated export with cloze deletion support.
    """
    lines: List[str] = [
        "#separator:tab",
        "#html:true",
        "#notetype:Basic (and reversed card)",
        "#columns:Front\tBack\tTags\tContext",
    ]
    for c in cards:
        term = (c.get("term") or "").replace("\t", " ").replace("\n", " ")
        translation = (c.get("translation") or "").replace("\t", " ").replace("\n", " ")
        phonetic = (c.get("phonetic") or "").replace("\t", " ")
        context = (c.get("context_sentence") or c.get("context") or "").replace("\t", " ").replace("\n", " ")
        tags_raw = c.get("tags") or ""
        collection = (c.get("collection") or "General").strip().replace(" ", "_")

        # Cloze representation if context contains the term
        cloze_ctx = ""
        if context and term and term.lower() in context.lower():
            cloze_ctx = re.sub(re.escape(term), f"{{{{c1::{term}}}}}", context, flags=re.IGNORECASE)

        tag_parts = [f"collection_{collection}"] + [
            t.strip().replace(" ", "_")
            for t in tags_raw.split(",") if t.strip()
        ]
        tags_str = " ".join(tag_parts)

        front = term if not phonetic else f"{term}  [{phonetic}]"
        back = translation

        lines.append(f"{front}\t{back}\t{tags_str}\t{cloze_ctx or context}")

    return ("\n".join(lines) + "\n").encode("utf-8")


def export_markdown(cards: List[Dict[str, Any]]) -> bytes:
    """Human-readable Markdown export, grouped by collection."""
    now_str = datetime.now(timezone.utc).strftime("%Y-%m-%d %H:%M UTC")
    lines: List[str] = [
        f"# 📚 Vocabulary Export — {now_str}",
        f"**Total cards:** {len(cards)}",
        "",
    ]

    by_collection: Dict[str, List[Dict[str, Any]]] = {}
    for c in cards:
        col = (c.get("collection") or "General").strip()
        by_collection.setdefault(col, []).append(c)

    for collection, col_cards in sorted(by_collection.items()):
        lines.append(f"## {collection} ({len(col_cards)} cards)")
        lines.append("")
        lines.append("| Term | Translation | Phonetic | Tags |")
        lines.append("|------|-------------|----------|------|")
        for c in col_cards:
            term = (c.get("term") or "").replace("|", "\\|")
            translation = (c.get("translation") or "").replace("|", "\\|")
            phonetic = (c.get("phonetic") or "").replace("|", "\\|")
            tags = (c.get("tags") or "").replace("|", "\\|")
            lines.append(f"| **{term}** | {translation} | {phonetic} | {tags} |")
        lines.append("")
        lines.append("### Details")
        lines.append("")
        for c in col_cards:
            term = c.get("term") or ""
            phonetic_str = f" `{c['phonetic']}`" if c.get("phonetic") else ""
            pos_str = f" *({c['part_of_speech']})*" if c.get("part_of_speech") else ""
            lines.append(f"### {term}{phonetic_str}{pos_str}")
            lines.append(f"- **Перевод**: {c.get('translation') or '—'}")
            if c.get("definition_en"):
                lines.append(f"- **Толкование**: {c['definition_en']}")
            if c.get("context_sentence") or c.get("context"):
                lines.append(f"- **Контекст**: *\"{c.get('context_sentence') or c.get('context')}\"*")
            if c.get("notes"):
                lines.append(f"- **Заметка**: {c['notes']}")
            lines.append("")

    return ("\n".join(lines) + "\n").encode("utf-8")