# License: Apache-2.0 License
# Created by: Patrick Lumbantobing, VertoX-AI
# Copyright (c) 2026 VertoX-AI. All rights reserved.
#
# This work is licensed under the Apache-2.0 License.
# To view a copy of this license, visit
# https://www.apache.org/licenses/LICENSE-2.0

"""Assemble and deterministically render backend-neutral benchmark reports."""

from __future__ import annotations

import csv
import io
import json
import os
import tempfile
from collections.abc import Mapping
from dataclasses import asdict, dataclass
from pathlib import Path
from typing import Literal

from speech_text_data_aligners.benchmarking.metrics import (
    BenchmarkObservation,
    GoldMetrics,
    PairwiseMetrics,
)
from speech_text_data_aligners.core.errors import BenchmarkError
from speech_text_data_aligners.core.validation import find_path_aliases

ReportFormat = Literal["json", "csv", "markdown"]


@dataclass(frozen=True, slots=True)
class BackendReport:
    """Bundle one backend's ordered observations and supported gold metrics.

    Parameters
    ----------
        backend_name: Stable backend report name.
        observations: Ordered neutral row observations.
        gold_metrics: Aggregate supported reference/runtime metrics.

    """

    backend_name: str
    observations: tuple[BenchmarkObservation, ...]
    gold_metrics: GoldMetrics


@dataclass(frozen=True, slots=True)
class BenchmarkReport:
    """Bundle deterministic per-backend and pairwise benchmark results.

    Parameters
    ----------
        backend_reports: Ordered backend reports.
        pairwise_metrics: Deterministically ordered backend-pair comparisons.

    """

    backend_reports: tuple[BackendReport, ...]
    pairwise_metrics: tuple[PairwiseMetrics, ...] = ()


def _metric_rows(report: BenchmarkReport) -> list[tuple[str, str, str]]:
    """Flatten headline metrics for CSV and Markdown renderers.

    Parameters
    ----------
        report: Typed benchmark report.

    Returns
    -------
        Ordered ``scope, metric, value`` rows.

    """
    rows: list[tuple[str, str, str]] = []
    for backend in report.backend_reports:
        metrics = backend.gold_metrics
        values: tuple[tuple[str, object], ...] = (
            ("success_count", metrics.success_count),
            ("failure_count", metrics.failure_count),
            ("referenced_rows", metrics.referenced_rows),
            ("missing_reference_rows", metrics.missing_reference_rows),
            ("text_reference_count", metrics.text_reference_count),
            ("missing_text_reference_count", metrics.missing_text_reference_count),
            ("exact_text_match_count", metrics.exact_text_match_count),
            ("exact_text_match_rate", metrics.exact_text_match_rate),
            ("first_end_reference_count", metrics.first_end_reference_count),
            (
                "missing_first_end_reference_count",
                metrics.missing_first_end_reference_count,
            ),
            ("first_end_scored_count", metrics.first_end_errors.count),
            ("first_end_mae_s", metrics.first_end_errors.mae),
            ("first_end_median_s", metrics.first_end_errors.median),
            ("first_end_max_s", metrics.first_end_errors.maximum),
            ("total_runtime_s", metrics.total_runtime_s),
            ("mean_runtime_s", metrics.mean_runtime_s),
        )
        rows.extend(
            (backend.backend_name, name, "" if value is None else str(value))
            for name, value in values
        )
        artifacts = dict.fromkeys(
            artifact
            for observation in backend.observations
            for artifact in observation.native_artifacts
        )
        rows.extend(
            (backend.backend_name, f"native_artifact_{index}", artifact)
            for index, artifact in enumerate(artifacts, start=1)
        )
    for pairwise in report.pairwise_metrics:
        scope = f"{pairwise.backend_a} vs {pairwise.backend_b}"
        rows.append((scope, "comparable_rows", str(pairwise.comparable_rows)))
        for name, summary in (
            ("first_start", pairwise.first_start),
            ("first_end", pairwise.first_end),
            ("last_start", pairwise.last_start),
            ("last_end", pairwise.last_end),
        ):
            rows.append(
                (
                    scope,
                    f"{name}_mae_s",
                    "" if summary.mae is None else str(summary.mae),
                )
            )
    return rows


def render_report(report: BenchmarkReport, output_format: ReportFormat) -> str:
    """Render a typed report as canonical JSON, CSV, or concise Markdown.

    Parameters
    ----------
        report: Backend-neutral benchmark report.
        output_format: One of ``json``, ``csv``, or ``markdown``.

    Returns
    -------
        Deterministically ordered newline-terminated report text.

    Raises
    ------
        BenchmarkError: If an unsupported format is supplied at runtime.

    """
    if output_format == "json":
        return (
            json.dumps(
                asdict(report),
                sort_keys=True,
                separators=(",", ":"),
                ensure_ascii=False,
            )
            + "\n"
        )
    rows = _metric_rows(report)
    if output_format == "csv":
        stream = io.StringIO(newline="")
        writer = csv.writer(stream, lineterminator="\n")
        writer.writerow(("scope", "metric", "value"))
        writer.writerows(rows)
        return stream.getvalue()
    if output_format == "markdown":
        lines = ["| Scope | Metric | Value |", "|---|---|---:|"]
        lines.extend(
            f"| {scope} | {metric} | {value} |" for scope, metric, value in rows
        )
        return "\n".join(lines) + "\n"
    raise BenchmarkError(f"unsupported report format: {output_format}")


def _write_text(path: Path, content: str, *, overwrite: bool) -> None:
    """Atomically publish one report text artifact.

    Parameters
    ----------
        path: Destination path.
        content: Fully rendered text.
        overwrite: Explicit replacement authorization.

    Raises
    ------
        BenchmarkError: If the destination exists or publication fails.

    """
    if path.exists() and not overwrite:
        raise BenchmarkError(f"report exists and overwrite was not authorized: {path}")
    path.parent.mkdir(parents=True, exist_ok=True)
    temporary_path: Path | None = None
    try:
        with tempfile.NamedTemporaryFile(
            mode="w",
            encoding="utf-8",
            newline="\n",
            dir=path.parent,
            prefix=f".{path.name}.",
            suffix=".tmp",
            delete=False,
        ) as stream:
            temporary_path = Path(stream.name)
            stream.write(content)
            stream.flush()
            os.fsync(stream.fileno())
        os.replace(temporary_path, path)
    except OSError as error:
        if temporary_path is not None:
            temporary_path.unlink(missing_ok=True)
        raise BenchmarkError(f"cannot publish benchmark report: {path}") from error


def report_bundle_paths(base_path: Path) -> tuple[Path, Path, Path]:
    """Derive the three deterministic report targets from one file prefix.

    Parameters
    ----------
        base_path: File prefix whose existing suffix is replaced per format.

    Returns
    -------
        JSON, CSV, and Markdown target paths in that order.

    """
    return (
        base_path.with_suffix(".json"),
        base_path.with_suffix(".csv"),
        base_path.with_suffix(".md"),
    )


def preflight_report_bundle(
    base_path: Path,
    *,
    metadata_csv: Path,
    reference_csv: Path,
    overwrite: bool = False,
) -> tuple[Path, Path, Path]:
    """Validate all report targets against immutable benchmark inputs and each other.

    Parameters
    ----------
        base_path: File prefix used to derive the report destinations.
        metadata_csv: Immutable benchmark metadata input.
        reference_csv: Immutable sparse reference input.
        overwrite: Whether existing, non-input report targets may be replaced.

    Returns
    -------
        Validated JSON, CSV, and Markdown target paths in that order.

    Raises
    ------
        BenchmarkError: If a target aliases an input/another target or exists without
            overwrite authorization.

    Side Effects:
        Reads filesystem identity/existence metadata only; no report is published.

    """
    targets = report_bundle_paths(base_path)
    named_paths: Mapping[str, Path] = {
        "metadata CSV": metadata_csv,
        "reference CSV": reference_csv,
        "report JSON": targets[0],
        "report CSV": targets[1],
        "report Markdown": targets[2],
    }
    aliases = tuple(
        pair
        for pair in find_path_aliases(named_paths)
        if not all(name in {"metadata CSV", "reference CSV"} for name in pair)
    )
    if aliases:
        left, right = aliases[0]
        raise BenchmarkError(f"benchmark artifact paths alias: {left} and {right}")
    if not overwrite and any(path.exists() for path in targets):
        raise BenchmarkError("one or more report targets already exist")
    return targets


def write_report_bundle(
    report: BenchmarkReport,
    base_path: Path,
    *,
    metadata_csv: Path,
    reference_csv: Path,
    overwrite: bool = False,
) -> tuple[Path, Path, Path]:
    """Write matching JSON, CSV, and Markdown reports from one typed result.

    Parameters
    ----------
        report: Typed benchmark result.
        base_path: File prefix; existing suffix is replaced for each format.
        metadata_csv: Immutable metadata input that targets must not alias.
        reference_csv: Immutable reference input that targets must not alias.
        overwrite: Explicitly permit replacement of existing report files.

    Returns
    -------
        JSON, CSV, and Markdown output paths in that order.

    Raises
    ------
        BenchmarkError: If targets collide, exist without authorization, or publication
            fails.

    Side Effects:
        Atomically writes three small report artifacts. Targets are preflighted before
        the first write so unauthorized overwrite cannot create a partial bundle.

    """
    targets = preflight_report_bundle(
        base_path,
        metadata_csv=metadata_csv,
        reference_csv=reference_csv,
        overwrite=overwrite,
    )
    formats: tuple[ReportFormat, ...] = ("json", "csv", "markdown")
    for path, output_format in zip(targets, formats, strict=True):
        _write_text(path, render_report(report, output_format), overwrite=overwrite)
    return targets