from __future__ import annotations

import json
import re
from collections import OrderedDict
from collections.abc import Iterable
from pathlib import Path

from .streaming import CorpusPlanEntry, StreamDocument, iter_corpus_plan_documents


DEFAULT_CACHE_BYTE_LIMIT = 3 * 1024 * 1024 * 1024
DEFAULT_SHARD_BYTE_LIMIT = 256 * 1024 * 1024
_SAFE_NAME_PATTERN = re.compile(r"[^A-Za-z0-9_.-]+")


def _safe_source_name(name: str) -> str:
    cleaned = _SAFE_NAME_PATTERN.sub("-", name.strip()).strip("-._")
    return cleaned or "source"


def _jsonl_bytes(record: dict[str, object]) -> bytes:
    return (json.dumps(record, ensure_ascii=False, separators=(",", ":")) + "\n").encode("utf-8")


def _file_entry_for_group(
    *,
    source: str,
    path: Path,
    document: StreamDocument,
    rows: int,
) -> dict[str, object]:
    return {
        "source": "file",
        "name": source,
        "path": str(path.resolve()),
        "limit": rows,
        "weight": document.weight,
        "readout_weight": document.readout_weight,
        "transition_weight": document.transition_weight,
        "min_words": 1,
        "max_words": 0,
        "min_alpha_ratio": 0.0,
        "allowed_languages": [],
        "streaming": True,
    }


def materialize_corpus_plan(
    plan: Iterable[CorpusPlanEntry],
    output_dir: str | Path,
    *,
    max_bytes: int = DEFAULT_CACHE_BYTE_LIMIT,
    shard_bytes: int = DEFAULT_SHARD_BYTE_LIMIT,
    log_every: int = 0,
) -> dict[str, object]:
    if max_bytes <= 0:
        raise ValueError("max_bytes must be positive.")
    if shard_bytes <= 0:
        raise ValueError("shard_bytes must be positive.")

    output = Path(output_dir)
    output.mkdir(parents=True, exist_ok=True)

    bytes_written = 0
    documents_written = 0
    source_counts: OrderedDict[str, int] = OrderedDict()
    file_entries: list[dict[str, object]] = []
    open_handles: dict[str, object] = {}
    open_paths: dict[str, Path] = {}
    open_sizes: dict[str, int] = {}
    shard_indices: dict[str, int] = {}
    first_documents: dict[str, StreamDocument] = {}

    def close_all() -> None:
        for handle in open_handles.values():
            handle.close()

    def open_next_shard(source: str) -> object:
        handle = open_handles.pop(source, None)
        if handle is not None:
            handle.close()
        shard_index = shard_indices.get(source, 0)
        shard_indices[source] = shard_index + 1
        path = output / f"{_safe_source_name(source)}-{shard_index:04d}.jsonl"
        open_paths[source] = path
        open_sizes[source] = 0
        new_handle = path.open("w", encoding="utf-8", newline="\n")
        open_handles[source] = new_handle
        return new_handle

    try:
        for document in iter_corpus_plan_documents(plan):
            source = document.source or "source"
            record = {
                "text": document.text,
                "language": document.language,
                "source": source,
            }
            if document.preference_rejected_text:
                record["preference_rejected_text"] = document.preference_rejected_text
            encoded = _jsonl_bytes(record)
            if bytes_written + len(encoded) > max_bytes:
                break

            handle = open_handles.get(source)
            if handle is None:
                handle = open_next_shard(source)
            if open_sizes[source] > 0 and open_sizes[source] + len(encoded) > shard_bytes:
                path = open_paths[source]
                rows = source_counts.get(str(path), 0)
                if rows > 0:
                    file_entries.append(
                        _file_entry_for_group(
                            source=source,
                            path=path,
                            document=first_documents[str(path)],
                            rows=rows,
                        )
                    )
                handle = open_next_shard(source)

            path_key = str(open_paths[source])
            if path_key not in first_documents:
                first_documents[path_key] = document
            handle.write(encoded.decode("utf-8"))
            open_sizes[source] += len(encoded)
            bytes_written += len(encoded)
            documents_written += 1
            source_counts[path_key] = source_counts.get(path_key, 0) + 1
            if log_every > 0 and documents_written % log_every == 0:
                print(
                    f"[materialize] wrote {documents_written} documents "
                    f"({bytes_written} bytes)",
                    flush=True,
                )
    finally:
        close_all()

    emitted_paths = {entry["path"] for entry in file_entries}
    for path_key, rows in source_counts.items():
        path = Path(path_key)
        if str(path.resolve()) in emitted_paths:
            continue
        if rows <= 0:
            continue
        source = path.stem.rsplit("-", 1)[0]
        file_entries.append(
            _file_entry_for_group(
                source=source,
                path=path,
                document=first_documents[path_key],
                rows=rows,
            )
        )

    plan_path = output / "materialized-plan.json"
    manifest_path = output / "materialized-manifest.json"
    plan_payload = {
        "schema_version": "reframr.materialized_plan.v1",
        "sources": file_entries,
        "notes": [
            "Materialized from a Reframr corpus plan with normalized JSONL rows.",
            "Raw upstream dataset repositories are not cached by this file.",
        ],
    }
    manifest = {
        "status": "materialized",
        "documents_written": documents_written,
        "bytes_written": bytes_written,
        "max_bytes": max_bytes,
        "shard_bytes": shard_bytes,
        "source_count": len(file_entries),
        "plan_path": str(plan_path.resolve()),
    }
    plan_path.write_text(json.dumps(plan_payload, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")
    manifest_path.write_text(json.dumps(manifest, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")
    return {**manifest, "manifest_path": str(manifest_path.resolve())}