from __future__ import annotations

from dataclasses import dataclass
from pathlib import Path
from typing import Any

from slop_farmer.data.parquet_io import read_json
from slop_farmer.data.search_duckdb import connect_pr_search_db, resolve_active_run
from slop_farmer.data.snapshot_paths import (
    ANALYSIS_REPORT_FILENAME_BY_VARIANT,
    CURRENT_ANALYSIS_MANIFEST_PATH,
    analysis_run_manifest_path,
    load_archived_analysis_run_manifest,
    load_current_analysis_manifest,
    repo_relative_path_to_local,
)

ANALYSIS_VARIANTS = {"auto", "deterministic", "hybrid"}


@dataclass(frozen=True, slots=True)
class ActiveSnapshotContext:
    active_run: dict[str, Any]
    snapshot_dir: Path


@dataclass(frozen=True, slots=True)
class AnalysisContext:
    active_run: dict[str, Any]
    report: dict[str, Any]
    report_path: Path
    report_source: str
    variant_requested: str
    variant_used: str
    analysis_id: str | None


def get_analysis_status(
    db_path: Path,
    *,
    repo: str | None = None,
    variant: str = "auto",
    snapshot_id: str | None = None,
    analysis_id: str | None = None,
) -> dict[str, Any]:
    active = _resolve_active_snapshot_context(db_path, repo=repo)
    report_path, variant_used, report_source, resolved_analysis_id = _resolve_analysis_report_path(
        active.snapshot_dir,
        variant,
        snapshot_id=snapshot_id,
        analysis_id=analysis_id,
        required=False,
    )
    payload = {
        "repo": str(active.active_run["repo"]),
        "active_snapshot_id": str(active.active_run["snapshot_id"]),
        "run_id": str(active.active_run["id"]),
        "variant_requested": _normalize_analysis_variant(variant),
        "available": report_path is not None,
    }
    if report_path is None or variant_used is None or report_source is None:
        return payload
    report = _load_report(report_path)
    status = {
        **payload,
        "snapshot_id": str(report.get("snapshot_id") or active.active_run["snapshot_id"]),
        "variant_used": variant_used,
        "analysis_source": report_source,
        "llm_enrichment": bool(report.get("llm_enrichment")),
        "generated_at": report.get("generated_at"),
        "counts": _analysis_counts(report),
    }
    if resolved_analysis_id is not None:
        status["analysis_id"] = resolved_analysis_id
    return status


def get_pr_analysis(
    db_path: Path,
    *,
    pr_number: int,
    repo: str | None = None,
    variant: str = "auto",
    snapshot_id: str | None = None,
    analysis_id: str | None = None,
) -> dict[str, Any]:
    context = _load_analysis_context(
        db_path,
        repo=repo,
        variant=variant,
        snapshot_id=snapshot_id,
        analysis_id=analysis_id,
    )
    meta_bug, rank = _find_meta_bug_for_pr(context.report, pr_number)
    duplicate_pr = _find_duplicate_pr_for_pr(context.report, pr_number)
    return {
        **_analysis_base_payload(context),
        "pr_number": pr_number,
        "found": meta_bug is not None or duplicate_pr is not None,
        "meta_bug": None if meta_bug is None else _meta_bug_payload(meta_bug, rank=rank),
        "duplicate_pr": duplicate_pr,
    }


def list_analysis_meta_bugs(
    db_path: Path,
    *,
    repo: str | None = None,
    variant: str = "auto",
    limit: int = 50,
    snapshot_id: str | None = None,
    analysis_id: str | None = None,
) -> dict[str, Any]:
    context = _load_analysis_context(
        db_path,
        repo=repo,
        variant=variant,
        snapshot_id=snapshot_id,
        analysis_id=analysis_id,
    )
    meta_bugs = [
        _meta_bug_payload(cluster, rank=index)
        for index, cluster in enumerate(context.report.get("meta_bugs", [])[:limit], start=1)
    ]
    return {
        **_analysis_base_payload(context),
        "meta_bugs": meta_bugs,
        "meta_bug_count": len(meta_bugs),
    }


def get_analysis_meta_bug(
    db_path: Path,
    *,
    cluster_id: str,
    repo: str | None = None,
    variant: str = "auto",
    snapshot_id: str | None = None,
    analysis_id: str | None = None,
) -> dict[str, Any]:
    context = _load_analysis_context(
        db_path,
        repo=repo,
        variant=variant,
        snapshot_id=snapshot_id,
        analysis_id=analysis_id,
    )
    for index, cluster in enumerate(context.report.get("meta_bugs", []), start=1):
        if str(cluster.get("cluster_id")) != cluster_id:
            continue
        return {
            **_analysis_base_payload(context),
            "meta_bug": _meta_bug_payload(cluster, rank=index),
            "duplicate_pr": _find_duplicate_pr_by_cluster_id(context.report, cluster_id),
        }
    raise ValueError(f"Analysis cluster {cluster_id!r} was not found in the active analysis view.")


def list_analysis_duplicate_prs(
    db_path: Path,
    *,
    repo: str | None = None,
    variant: str = "auto",
    limit: int = 50,
    snapshot_id: str | None = None,
    analysis_id: str | None = None,
) -> dict[str, Any]:
    context = _load_analysis_context(
        db_path,
        repo=repo,
        variant=variant,
        snapshot_id=snapshot_id,
        analysis_id=analysis_id,
    )
    duplicate_prs = [
        {"rank": index, **dict(entry)}
        for index, entry in enumerate(context.report.get("duplicate_prs", [])[:limit], start=1)
    ]
    return {
        **_analysis_base_payload(context),
        "duplicate_prs": duplicate_prs,
        "duplicate_pr_count": len(duplicate_prs),
    }


def get_analysis_best(
    db_path: Path,
    *,
    repo: str | None = None,
    variant: str = "auto",
    snapshot_id: str | None = None,
    analysis_id: str | None = None,
) -> dict[str, Any]:
    context = _load_analysis_context(
        db_path,
        repo=repo,
        variant=variant,
        snapshot_id=snapshot_id,
        analysis_id=analysis_id,
    )
    return {
        **_analysis_base_payload(context),
        "best_issue": _best_entry_with_cluster_id(
            context.report,
            context.report.get("best_issue"),
            number_key="issue_number",
            numbers_key="issue_numbers",
        ),
        "best_pr": _best_entry_with_cluster_id(
            context.report,
            context.report.get("best_pr"),
            number_key="pr_number",
            numbers_key="pr_numbers",
        ),
    }


def _resolve_active_snapshot_context(
    db_path: Path,
    *,
    repo: str | None,
) -> ActiveSnapshotContext:
    connection = connect_pr_search_db(db_path, read_only=True)
    try:
        active_run = resolve_active_run(connection, repo=repo)
    finally:
        connection.close()
    return ActiveSnapshotContext(
        active_run={str(key): value for key, value in active_run.items()},
        snapshot_dir=Path(str(active_run["snapshot_dir"])).resolve(),
    )


def _load_analysis_context(
    db_path: Path,
    *,
    repo: str | None,
    variant: str,
    snapshot_id: str | None,
    analysis_id: str | None,
) -> AnalysisContext:
    active = _resolve_active_snapshot_context(db_path, repo=repo)
    report_path, variant_used, report_source, resolved_analysis_id = _resolve_analysis_report_path(
        active.snapshot_dir,
        variant,
        snapshot_id=snapshot_id,
        analysis_id=analysis_id,
        required=True,
    )
    assert report_path is not None
    assert variant_used is not None
    assert report_source is not None
    return AnalysisContext(
        active_run=active.active_run,
        report=_load_report(report_path),
        report_path=report_path,
        report_source=report_source,
        variant_requested=_normalize_analysis_variant(variant),
        variant_used=variant_used,
        analysis_id=resolved_analysis_id,
    )


def _resolve_analysis_report_path(
    snapshot_dir: Path,
    variant: str,
    *,
    snapshot_id: str | None,
    analysis_id: str | None,
    required: bool,
) -> tuple[Path | None, str | None, str | None, str | None]:
    normalized = _normalize_analysis_variant(variant)
    if (snapshot_id is None) != (analysis_id is None):
        raise ValueError("snapshot_id and analysis_id must be provided together.")
    if snapshot_id is not None and analysis_id is not None:
        selection = _resolve_archived_analysis_report_path(
            snapshot_dir,
            snapshot_id=snapshot_id,
            analysis_id=analysis_id,
            variant=normalized,
        )
        if selection is not None:
            return (*selection, analysis_id)
        if not required:
            return None, None, None, None
        raise ValueError(
            f"Published analysis run {analysis_id!r} for snapshot {snapshot_id!r} was not found."
        )

    current_manifest_path = repo_relative_path_to_local(
        snapshot_dir, CURRENT_ANALYSIS_MANIFEST_PATH
    )
    if normalized == "deterministic":
        selection = _resolve_snapshot_local_report_path(snapshot_dir, variant=normalized)
        if selection is not None:
            return (*selection, None)

    if current_manifest_path.exists():
        report_path, variant_used = _resolve_manifest_report_path(
            snapshot_dir,
            load_current_analysis_manifest(current_manifest_path),
            variant=normalized,
            manifest_kind="current",
        )
        return (
            report_path,
            variant_used,
            "current",
            str(load_current_analysis_manifest(current_manifest_path)["analysis_id"]),
        )

    selection = _resolve_snapshot_local_report_path(snapshot_dir, variant=normalized)
    if selection is not None:
        return (*selection, None)
    if not required:
        return None, None, None, None
    raise ValueError(
        "No analysis report was found for the current analysis view or active snapshot."
    )


def _resolve_archived_analysis_report_path(
    snapshot_dir: Path,
    *,
    snapshot_id: str,
    analysis_id: str,
    variant: str,
) -> tuple[Path, str, str] | None:
    manifest_path = repo_relative_path_to_local(
        snapshot_dir,
        analysis_run_manifest_path(snapshot_id, analysis_id),
    )
    if not manifest_path.exists():
        return None
    report_path, variant_used = _resolve_manifest_report_path(
        snapshot_dir,
        load_archived_analysis_run_manifest(manifest_path),
        variant=variant,
        manifest_kind="archived",
    )
    return report_path, variant_used, "archived"


def _resolve_manifest_report_path(
    snapshot_dir: Path,
    manifest: dict[str, Any],
    *,
    variant: str,
    manifest_kind: str,
) -> tuple[Path, str]:
    artifact_key = _artifact_key_for_variant(variant, manifest_kind=manifest_kind)
    artifacts = manifest.get("artifacts") or {}
    artifact_path = artifacts.get(artifact_key)
    if not isinstance(artifact_path, str) or not artifact_path:
        message = (
            f"Published {manifest_kind} analysis manifest does not provide the {variant} artifact."
            if variant != "auto"
            else f"Published {manifest_kind} analysis manifest does not provide the canonical hybrid artifact."
        )
        raise ValueError(message)
    report_path = repo_relative_path_to_local(snapshot_dir, artifact_path)
    if not report_path.exists():
        raise ValueError(
            f"Published {manifest_kind} analysis artifact {artifact_path!r} is missing from the materialized snapshot."
        )
    variant_used = "hybrid" if artifact_key == "hybrid" else variant
    return report_path, variant_used


def _artifact_key_for_variant(variant: str, *, manifest_kind: str) -> str:
    if variant == "auto":
        return "hybrid"
    if variant == "hybrid":
        return "hybrid"
    raise ValueError(
        f"Published {manifest_kind} analysis only serves canonical hybrid artifacts; requested {variant!r}."
    )


def _resolve_snapshot_local_report_path(
    snapshot_dir: Path,
    *,
    variant: str,
) -> tuple[Path, str, str] | None:
    if variant == "auto":
        hybrid_path = snapshot_dir / ANALYSIS_REPORT_FILENAME_BY_VARIANT["hybrid"]
        if hybrid_path.exists():
            return hybrid_path, "hybrid", "snapshot"
        deterministic_path = snapshot_dir / ANALYSIS_REPORT_FILENAME_BY_VARIANT["deterministic"]
        if deterministic_path.exists():
            return deterministic_path, "deterministic", "snapshot"
        return None
    report_path = snapshot_dir / ANALYSIS_REPORT_FILENAME_BY_VARIANT[variant]
    if not report_path.exists():
        return None
    return report_path, variant, "snapshot"


def _normalize_analysis_variant(variant: str) -> str:
    normalized = variant.strip().lower()
    if normalized not in ANALYSIS_VARIANTS:
        raise ValueError(
            f"Unsupported analysis variant {variant!r}; expected auto, hybrid, or deterministic."
        )
    return normalized


def _analysis_base_payload(context: AnalysisContext) -> dict[str, Any]:
    active_snapshot_id = str(context.active_run["snapshot_id"])
    snapshot_id = str(context.report.get("snapshot_id") or active_snapshot_id)
    payload = {
        "repo": str(context.active_run["repo"]),
        "snapshot_id": snapshot_id,
        "active_snapshot_id": active_snapshot_id,
        "run_id": str(context.active_run["id"]),
        "variant_requested": context.variant_requested,
        "variant_used": context.variant_used,
        "analysis_source": context.report_source,
        "llm_enrichment": bool(context.report.get("llm_enrichment")),
        "generated_at": context.report.get("generated_at"),
    }
    if context.analysis_id is not None:
        payload["analysis_id"] = context.analysis_id
    return payload


def _analysis_counts(report: dict[str, Any]) -> dict[str, int]:
    return {
        "meta_bugs": len(report.get("meta_bugs") or []),
        "duplicate_issues": len(report.get("duplicate_issues") or []),
        "duplicate_prs": len(report.get("duplicate_prs") or []),
    }


def _meta_bug_payload(cluster: dict[str, Any], *, rank: int | None = None) -> dict[str, Any]:
    payload = dict(cluster)
    if rank is not None:
        payload["rank"] = rank
    return payload


def _find_meta_bug_for_pr(
    report: dict[str, Any],
    pr_number: int,
) -> tuple[dict[str, Any] | None, int | None]:
    for index, cluster in enumerate(report.get("meta_bugs", []), start=1):
        pr_numbers = {int(number) for number in cluster.get("pr_numbers", [])}
        if pr_number in pr_numbers:
            return dict(cluster), index
    return None, None


def _find_duplicate_pr_for_pr(report: dict[str, Any], pr_number: int) -> dict[str, Any] | None:
    for entry in report.get("duplicate_prs", []):
        numbers = {
            int(entry["canonical_pr_number"]),
            *(int(number) for number in entry.get("duplicate_pr_numbers", [])),
        }
        if pr_number in numbers:
            return dict(entry)
    return None


def _find_duplicate_pr_by_cluster_id(
    report: dict[str, Any],
    cluster_id: str,
) -> dict[str, Any] | None:
    for entry in report.get("duplicate_prs", []):
        if str(entry.get("cluster_id")) == cluster_id:
            return dict(entry)
    return None


def _best_entry_with_cluster_id(
    report: dict[str, Any],
    entry: Any,
    *,
    number_key: str,
    numbers_key: str,
) -> dict[str, Any] | None:
    if not isinstance(entry, dict):
        return None
    number = entry.get(number_key)
    if number is None:
        return dict(entry)
    for cluster in report.get("meta_bugs", []):
        numbers = {int(value) for value in cluster.get(numbers_key, [])}
        if int(number) in numbers:
            return {"cluster_id": cluster.get("cluster_id"), **dict(entry)}
    return dict(entry)


def _load_report(path: Path) -> dict[str, Any]:
    payload = read_json(path)
    if not isinstance(payload, dict):
        raise ValueError(f"Analysis report at {path} must contain a JSON object.")
    return {str(key): value for key, value in payload.items()}