from __future__ import annotations

import json
import os
import urllib.error
import urllib.request
from collections import Counter
from datetime import datetime, timezone
from pathlib import Path
from typing import Any

import yaml

DEFAULT_FRESHNESS_DAYS = 7

from reuse_surface import hub_client
from reuse_surface.registry import (
    LEVEL_ORDERS,
    entry_vector,
    load_index_at,
    parse_front_matter,
    parse_vector,
    registry_paths,
    vectors_match,
)


def _histogram(values: list[str], order: list[str]) -> dict[str, int]:
    counts = Counter(values)
    return {level: counts.get(level, 0) for level in order if counts.get(level, 0)}


def _probe_url(url: str) -> dict[str, Any]:
    request = urllib.request.Request(
        url,
        method="HEAD",
        headers={"User-Agent": "reuse-surface/0.1"},
    )
    try:
        with urllib.request.urlopen(request, timeout=30) as response:
            return {
                "url": url,
                "status": response.status,
                "content_type": response.headers.get("Content-Type", ""),
                "ok": response.status == 200,
            }
    except urllib.error.HTTPError as exc:
        return {
            "url": url,
            "status": exc.code,
            "content_type": exc.headers.get("Content-Type", ""),
            "ok": False,
        }
    except urllib.error.URLError as exc:
        return {"url": url, "status": None, "error": str(exc.reason), "ok": False}


def collect_stats(
    repo_root: Path,
    *,
    federation_ready: bool = False,
    raw_url: str | None = None,
    hub_url: str | None = None,
) -> dict[str, Any]:
    paths = registry_paths(repo_root)
    stats: dict[str, Any] = {
        "repo_root": str(repo_root),
        "registry_present": paths["registry"].exists(),
        "index_present": paths["index"].exists(),
        "sources_present": paths["sources"].exists(),
        "capability_count": 0,
        "histograms": {},
        "reliability": {"r0_r2": 0, "r3_plus": 0},
        "consumption_modes": {},
        "vector_drift": [],
        "federation": {},
        "hub": {},
    }

    if not paths["index"].exists():
        if federation_ready and raw_url:
            stats["federation"]["raw_url_probe"] = _probe_url(raw_url)
        if hub_url or _hub_configured():
            stats["hub"] = _hub_summary(hub_url)
        return stats

    index = load_index_at(paths["index"])
    capabilities = index.get("capabilities", [])
    stats["capability_count"] = len(capabilities)
    stats["domain"] = index.get("domain")

    discovery: list[str] = []
    availability: list[str] = []
    completeness: list[str] = []
    reliability: list[str] = []
    mode_counts: Counter[str] = Counter()

    for row in capabilities:
        vector = parse_vector(row["vector"])
        discovery.append(vector["discovery"])
        availability.append(vector["availability"])
        completeness.append(vector["completeness"])
        reliability.append(vector["reliability"])
        for mode in row.get("consumption_modes", []):
            mode_counts[mode] += 1

        entry_path = repo_root / row["path"]
        if entry_path.exists():
            try:
                front_matter = parse_front_matter(entry_path)
                if not vectors_match(row["vector"], front_matter):
                    stats["vector_drift"].append(
                        {
                            "id": row["id"],
                            "index_vector": row["vector"],
                            "entry_vector": entry_vector(front_matter),
                        }
                    )
            except ValueError:
                stats["vector_drift"].append(
                    {"id": row["id"], "error": "invalid entry front matter"}
                )

    stats["histograms"] = {
        "discovery": _histogram(discovery, LEVEL_ORDERS["discovery"]),
        "availability": _histogram(availability, LEVEL_ORDERS["availability"]),
        "completeness": _histogram(completeness, LEVEL_ORDERS["completeness"]),
        "reliability": _histogram(reliability, LEVEL_ORDERS["reliability"]),
    }
    stats["reliability"] = {
        "r0_r2": sum(1 for level in reliability if level in {"R0", "R1", "R2"}),
        "r3_plus": sum(1 for level in reliability if level_at_least_reliability(level, "R3")),
    }
    stats["consumption_modes"] = dict(sorted(mode_counts.items()))

    if federation_ready:
        probe_url = raw_url
        if not probe_url and paths["index"].exists():
            probe_url = _default_raw_url(repo_root)
        if probe_url:
            stats["federation"]["raw_url_probe"] = _probe_url(probe_url)
        stats["federation"]["index_valid_yaml"] = _index_yaml_valid(paths["index"])

    stats["hub"] = _hub_summary(hub_url)
    return stats


def level_at_least_reliability(current: str, minimum: str) -> bool:
    order = LEVEL_ORDERS["reliability"]
    return order.index(current) >= order.index(minimum)


def _hub_configured() -> bool:
    return bool(os.environ.get("REUSE_SURFACE_URL"))


def _freshness_days() -> int:
    raw = os.environ.get("REUSE_SURFACE_FRESHNESS_DAYS")
    if raw:
        try:
            return int(raw)
        except ValueError:
            pass
    return DEFAULT_FRESHNESS_DAYS


def _composed_at_age_days(composed_at: str | None) -> float | None:
    if not composed_at:
        return None
    try:
        composed_dt = datetime.fromisoformat(composed_at.replace("Z", "+00:00"))
    except ValueError:
        return None
    now = datetime.now(timezone.utc)
    return (now - composed_dt).total_seconds() / 86400


def _hub_summary(hub_url: str | None) -> dict[str, Any]:
    try:
        status, payload = hub_client.hub_list(hub_url)
    except (ValueError, urllib.error.URLError, OSError):
        return {"configured": False}
    if status != 200:
        return {"configured": True, "status": status, "error": payload}
    repos = payload.get("repos", [])
    summary: dict[str, Any] = {
        "configured": True,
        "registration_count": payload.get("count", len(repos)),
        "enabled_count": sum(1 for repo in repos if repo.get("enabled", True)),
    }

    try:
        f_status, f_payload = hub_client.hub_federated(hub_url)
    except (ValueError, urllib.error.URLError, OSError):
        f_status, f_payload = None, None
    if f_status == 200 and isinstance(f_payload, dict):
        composed_at = f_payload.get("composed_at")
        stale = f_payload.get("stale", False)
        age_days = _composed_at_age_days(composed_at)
        threshold = _freshness_days()
        summary["composed_at"] = composed_at
        summary["stale"] = stale
        summary["age_days"] = round(age_days, 2) if age_days is not None else None
        summary["freshness_threshold_days"] = threshold
        summary["stale_warning"] = bool(stale) or (age_days is not None and age_days > threshold)

    return summary


def _default_raw_url(repo_root: Path) -> str | None:
    return None


def _index_yaml_valid(index_path: Path) -> bool:
    try:
        data = load_index_at(index_path)
        return isinstance(data, dict) and "capabilities" in data
    except (OSError, yaml.YAMLError):
        return False


def format_stats_markdown(stats: dict[str, Any]) -> str:
    lines = ["# Registry stats", ""]
    lines.append(f"**Repo:** `{stats['repo_root']}`")
    lines.append(f"**Capabilities:** {stats['capability_count']}")
    if stats.get("domain"):
        lines.append(f"**Domain:** `{stats['domain']}`")
    lines.append("")

    lines.append("## Layout")
    lines.append(f"- registry present: `{stats['registry_present']}`")
    lines.append(f"- index present: `{stats['index_present']}`")
    lines.append(f"- federation sources present: `{stats['sources_present']}`")
    lines.append("")

    rel = stats["reliability"]
    lines.append("## Reliability bands (index vectors)")
    lines.append(f"- R0–R2: **{rel['r0_r2']}**")
    lines.append(f"- R3+: **{rel['r3_plus']}**")
    lines.append("")

    for dimension, histogram in stats.get("histograms", {}).items():
        if not histogram:
            continue
        lines.append(f"## {dimension.title()} histogram")
        for level, count in histogram.items():
            lines.append(f"- `{level}`: {count}")
        lines.append("")

    if stats.get("consumption_modes"):
        lines.append("## Consumption modes")
        for mode, count in stats["consumption_modes"].items():
            lines.append(f"- `{mode}`: {count}")
        lines.append("")

    drift = stats.get("vector_drift", [])
    lines.append(f"## Vector drift: **{len(drift)}**")
    for item in drift[:10]:
        if "error" in item:
            lines.append(f"- `{item['id']}`: {item['error']}")
        else:
            lines.append(
                f"- `{item['id']}`: index `{item['index_vector']}` "
                f"≠ entry `{item['entry_vector']}`"
            )
    if len(drift) > 10:
        lines.append(f"- … and {len(drift) - 10} more")
    lines.append("")

    federation = stats.get("federation", {})
    if federation:
        lines.append("## Federation readiness")
        if "index_valid_yaml" in federation:
            lines.append(f"- index valid YAML: `{federation['index_valid_yaml']}`")
        probe = federation.get("raw_url_probe")
        if probe:
            status = probe.get("status")
            ok = probe.get("ok")
            lines.append(f"- raw URL probe: status **{status}** ({'ok' if ok else 'fail'})")
            lines.append(f"  `{probe.get('url', '')}`")
        lines.append("")

    hub = stats.get("hub", {})
    if hub.get("configured"):
        lines.append("## Hub")
        if "registration_count" in hub:
            lines.append(
                f"- registrations: **{hub['registration_count']}** "
                f"({hub.get('enabled_count', 0)} enabled)"
            )
        elif "error" in hub:
            lines.append(f"- hub error: {hub['error']}")
        if "composed_at" in hub:
            age = hub.get("age_days")
            age_text = f"{age:.2f}d ago" if age is not None else "unknown"
            warning = " ⚠ STALE" if hub.get("stale_warning") else ""
            lines.append(
                f"- federated index composed: `{hub['composed_at']}` ({age_text}, "
                f"threshold {hub.get('freshness_threshold_days')}d){warning}"
            )
        lines.append("")

    return "\n".join(lines) + "\n"


def format_stats_json(stats: dict[str, Any]) -> str:
    return json.dumps(stats, indent=2, sort_keys=True)


def collect_roster_stats(
    roster_path: Path,
    *,
    federation_ready: bool = False,
) -> dict[str, Any]:
    data = yaml.safe_load(roster_path.read_text(encoding="utf-8"))
    repos = data.get("repos", [])
    summary = data.get("summary", {})
    publish_fail = [r["slug"] for r in repos if r.get("publish_check") == "fail"]
    hub_missing = [r["slug"] for r in repos if not r.get("hub_registered")]
    pending = [r["slug"] for r in repos if r.get("status") != "established"]

    stats: dict[str, Any] = {
        "roster_path": str(roster_path),
        "workstation_root": data.get("workstation_root"),
        "definition": data.get("definition"),
        "summary": summary,
        "counts": {
            "total": summary.get("total", len(repos)),
            "established": summary.get("established", 0),
            "pending": summary.get("pending", 0),
            "hub_registered": summary.get("hub_registered", 0),
            "publish_pass": summary.get("publish_pass", 0),
            "publish_fail": summary.get("publish_fail", len(publish_fail)),
            "with_reuse_surface_seed": summary.get("with_reuse_surface_seed", 0),
        },
        "publish_fail_slugs": publish_fail,
        "hub_unregistered_slugs": hub_missing,
        "pending_slugs": pending,
        "federation_ready": federation_ready,
    }
    if federation_ready:
        total = stats["counts"]["total"] or len(repos)
        publish_pass = stats["counts"]["publish_pass"] or 0
        stats["federation_readiness"] = {
            "all_established": stats["counts"]["pending"] == 0,
            "all_hub_registered": len(hub_missing) == 0,
            "all_publish_pass": len(publish_fail) == 0,
            "publish_pass_ratio": f"{publish_pass}/{total}",
            "publish_sweep": summary.get("publish_sweep"),
        }
    return stats


def format_roster_stats_markdown(stats: dict[str, Any]) -> str:
    lines = ["# Workstation roster federation stats", ""]
    lines.append(f"**Roster:** `{stats['roster_path']}`")
    if stats.get("workstation_root"):
        lines.append(f"**Workstation root:** `{stats['workstation_root']}`")
    lines.append("")

    counts = stats["counts"]
    lines.append("## Summary")
    lines.append(f"- total repos: **{counts['total']}**")
    lines.append(f"- established: **{counts['established']}**")
    lines.append(f"- pending: **{counts['pending']}**")
    lines.append(f"- hub registered: **{counts['hub_registered']}**")
    lines.append(f"- publish pass: **{counts['publish_pass']}**")
    lines.append(f"- publish fail: **{counts['publish_fail']}**")
    lines.append("")

    if stats.get("federation_readiness"):
        fr = stats["federation_readiness"]
        lines.append("## Federation readiness")
        lines.append(f"- all established: `{fr['all_established']}`")
        lines.append(f"- all hub registered: `{fr['all_hub_registered']}`")
        lines.append(f"- all publish pass: `{fr['all_publish_pass']}`")
        lines.append(f"- publish pass ratio: **{fr['publish_pass_ratio']}**")
        if fr.get("publish_sweep"):
            lines.append(f"- last sweep: `{fr['publish_sweep']}`")
        lines.append("")

    if stats.get("publish_fail_slugs"):
        lines.append("## Publish fail")
        for slug in stats["publish_fail_slugs"]:
            lines.append(f"- `{slug}`")
        lines.append("")

    if stats.get("hub_unregistered_slugs"):
        lines.append("## Hub not registered")
        for slug in stats["hub_unregistered_slugs"]:
            lines.append(f"- `{slug}`")
        lines.append("")

    return "\n".join(lines) + "\n"


def format_roster_stats_json(stats: dict[str, Any]) -> str:
    return json.dumps(stats, indent=2, sort_keys=True)