"""
Dependency Generator — automatic discovery of control dependencies.

Three strategies:
  1. Ontology-based: same normalized_object + phase sequence -> prerequisite
  2. Pattern-based: known patterns (define->implement, implement->monitor, etc.)
  3. Domain packs: YAML-defined rules for specific regulatory domains
"""

from __future__ import annotations

import logging
import os
import re
from collections import defaultdict
from typing import Optional

import yaml

from services.dependency_engine import Dependency, DEFAULT_PRIORITIES

logger = logging.getLogger(__name__)


# ============================================================================
# PHASE ORDERING (imported from ontology)
# ============================================================================

from services.control_ontology import PHASE_ORDER


# ============================================================================
# PATTERN RULES
# ============================================================================

PATTERN_RULES: list[dict] = [
    {
        "name": "define_before_implement",
        "source_filter": {"action_type": "define"},
        "target_filter": {"action_type": "implement"},
        "match_on": "normalized_object",
        "dependency_type": "prerequisite",
        "condition": {},
        "effect": {"set_status": "review_required"},
        "priority": 50,
    },
    {
        "name": "implement_before_monitor",
        "source_filter": {"action_type_in": ["implement", "configure", "enforce"]},
        "target_filter": {"action_type_in": ["monitor", "review", "test"]},
        "match_on": "normalized_object",
        "dependency_type": "prerequisite",
        "condition": {},
        "effect": {"set_status": "review_required"},
        "priority": 50,
    },
    {
        "name": "define_before_enforce",
        "source_filter": {"action_type": "define"},
        "target_filter": {"action_type": "enforce"},
        "match_on": "normalized_object",
        "dependency_type": "prerequisite",
        "condition": {},
        "effect": {"set_status": "review_required"},
        "priority": 50,
    },
    {
        "name": "implement_before_validate",
        "source_filter": {"action_type_in": ["implement", "configure"]},
        "target_filter": {"action_type_in": ["validate", "verify"]},
        "match_on": "normalized_object",
        "dependency_type": "prerequisite",
        "condition": {},
        "effect": {"set_status": "review_required"},
        "priority": 50,
    },
    {
        "name": "train_before_review",
        "source_filter": {"action_type": "train"},
        "target_filter": {"action_type_in": ["review", "assess"]},
        "match_on": "normalized_object",
        "dependency_type": "prerequisite",
        "condition": {},
        "effect": {"set_status": "review_required"},
        "priority": 60,
    },
]


# ============================================================================
# HELPER: Parse merge_key into components
# ============================================================================

def _parse_merge_key(merge_key: str) -> dict:
    """Parse 'action_type:normalized_object:phase[:asset_scope]' into components."""
    parts = merge_key.split(":")
    result = {
        "action_type": parts[0] if len(parts) > 0 else "",
        "normalized_object": parts[1] if len(parts) > 1 else "",
        "phase": parts[2] if len(parts) > 2 else "",
        "asset_scope": parts[3] if len(parts) > 3 else "",
    }
    return result


def _get_control_merge_key(control: dict) -> str:
    """Extract merge_key from a control dict (from generation_metadata or top-level)."""
    mk = control.get("merge_key", "")
    if not mk:
        meta = control.get("generation_metadata", {})
        if isinstance(meta, str):
            try:
                import json
                meta = json.loads(meta)
            except (ValueError, TypeError):
                meta = {}
        mk = meta.get("merge_group_hint", "")
    return mk


# ============================================================================
# ONTOLOGY-BASED GENERATOR
# ============================================================================

def generate_ontology_dependencies(controls: list[dict]) -> list[Dependency]:
    """Generate prerequisite dependencies from lifecycle phase ordering.

    Rule: If two controls share the same normalized_object and control A's
    phase precedes control B's phase, then A is a prerequisite for B.

    Groups by normalized_object first (O(n) grouping, O(k^2) per group
    where k is typically 2-8).
    """
    # Group controls by normalized_object
    groups: dict[str, list[dict]] = defaultdict(list)

    for ctrl in controls:
        mk = _get_control_merge_key(ctrl)
        if not mk:
            continue
        parsed = _parse_merge_key(mk)
        obj = parsed["normalized_object"]
        if obj:
            ctrl["_parsed_mk"] = parsed
            ctrl["_phase_order"] = PHASE_ORDER.get(parsed["phase"], 6)
            groups[obj].append(ctrl)

    dependencies: list[Dependency] = []

    for obj, group in groups.items():
        if len(group) < 2:
            continue

        # Sort by phase order
        group.sort(key=lambda c: c["_phase_order"])

        # Create prerequisite edges between adjacent phases
        for i in range(len(group)):
            for j in range(i + 1, len(group)):
                a = group[i]
                b = group[j]
                if a["_phase_order"] < b["_phase_order"]:
                    dep = Dependency(
                        source_control_id=a.get("id", a.get("control_id", "")),
                        target_control_id=b.get("id", b.get("control_id", "")),
                        dependency_type="prerequisite",
                        condition={},
                        effect={"set_status": "review_required"},
                        priority=DEFAULT_PRIORITIES["prerequisite"],
                        generation_method="ontology",
                    )
                    dependencies.append(dep)

    return dependencies


# ============================================================================
# PATTERN-BASED GENERATOR
# ============================================================================

def _matches_filter(control: dict, filter_: dict) -> bool:
    """Check if a control matches a pattern filter."""
    parsed = control.get("_parsed_mk", {})
    action = parsed.get("action_type", "")

    if "action_type" in filter_:
        if action != filter_["action_type"]:
            return False

    if "action_type_in" in filter_:
        if action not in filter_["action_type_in"]:
            return False

    return True


def generate_pattern_dependencies(
    controls: list[dict],
    rules: Optional[list[dict]] = None,
) -> list[Dependency]:
    """Apply pattern rules to generate dependencies between controls."""
    if rules is None:
        rules = PATTERN_RULES

    # Pre-parse merge keys
    for ctrl in controls:
        if "_parsed_mk" not in ctrl:
            mk = _get_control_merge_key(ctrl)
            if mk:
                ctrl["_parsed_mk"] = _parse_merge_key(mk)
            else:
                ctrl["_parsed_mk"] = {}

    dependencies: list[Dependency] = []

    for rule in rules:
        sources = [c for c in controls if _matches_filter(c, rule["source_filter"])]
        targets = [c for c in controls if _matches_filter(c, rule["target_filter"])]

        match_on = rule.get("match_on")

        for src in sources:
            for tgt in targets:
                src_id = src.get("id", src.get("control_id", ""))
                tgt_id = tgt.get("id", tgt.get("control_id", ""))

                if src_id == tgt_id:
                    continue

                if match_on == "normalized_object":
                    src_obj = src.get("_parsed_mk", {}).get("normalized_object", "")
                    tgt_obj = tgt.get("_parsed_mk", {}).get("normalized_object", "")
                    if not src_obj or src_obj != tgt_obj:
                        continue

                dep = Dependency(
                    source_control_id=src_id,
                    target_control_id=tgt_id,
                    dependency_type=rule["dependency_type"],
                    condition=rule.get("condition", {}),
                    effect=rule.get("effect", {"set_status": "review_required"}),
                    priority=rule.get("priority", 100),
                    generation_method="pattern",
                )
                dependencies.append(dep)

    return dependencies


# ============================================================================
# DOMAIN PACK GENERATOR
# ============================================================================

def load_domain_pack(path: str) -> dict:
    """Load a YAML domain pack."""
    with open(path, "r", encoding="utf-8") as f:
        return yaml.safe_load(f) or {}


def _title_matches(title: str, patterns: list[str]) -> bool:
    """Check if a title contains any of the given patterns (case-insensitive)."""
    title_lower = title.lower()
    return any(p.lower() in title_lower for p in patterns)


def generate_domain_dependencies(
    controls: list[dict],
    domain_pack_dir: str = "",
) -> list[Dependency]:
    """Apply all domain packs to generate domain-specific dependencies."""
    if not domain_pack_dir:
        domain_pack_dir = os.path.join(
            os.path.dirname(os.path.dirname(__file__)), "data", "domain_packs"
        )

    if not os.path.isdir(domain_pack_dir):
        return []

    dependencies: list[Dependency] = []

    for filename in sorted(os.listdir(domain_pack_dir)):
        if not filename.endswith((".yaml", ".yml")):
            continue

        pack = load_domain_pack(os.path.join(domain_pack_dir, filename))
        rules = pack.get("rules", [])

        for rule in rules:
            src_match = rule.get("source_match", {})
            tgt_match = rule.get("target_match", {})

            src_title_patterns = src_match.get("title_contains", [])
            tgt_title_patterns = tgt_match.get("title_contains", [])

            sources = [
                c for c in controls
                if src_title_patterns and _title_matches(c.get("title", ""), src_title_patterns)
            ]
            targets = [
                c for c in controls
                if tgt_title_patterns and _title_matches(c.get("title", ""), tgt_title_patterns)
            ]

            for src in sources:
                for tgt in targets:
                    src_id = src.get("id", src.get("control_id", ""))
                    tgt_id = tgt.get("id", tgt.get("control_id", ""))
                    if src_id == tgt_id:
                        continue

                    dep = Dependency(
                        source_control_id=src_id,
                        target_control_id=tgt_id,
                        dependency_type=rule.get("dependency_type", "prerequisite"),
                        condition=rule.get("condition", {
                            "field": "source.status", "op": "==", "value": "pass",
                        }),
                        effect=rule.get("effect", {"set_status": "not_applicable"}),
                        priority=rule.get("priority", DEFAULT_PRIORITIES.get(
                            rule.get("dependency_type", "prerequisite"), 100
                        )),
                        generation_method="domain_pack",
                    )
                    dependencies.append(dep)

    return dependencies


# ============================================================================
# TOP-LEVEL GENERATOR
# ============================================================================

def generate_all_dependencies(
    controls: list[dict],
    enable_ontology: bool = True,
    enable_patterns: bool = True,
    enable_domain_packs: bool = True,
    domain_pack_dir: str = "",
) -> tuple[list[Dependency], dict]:
    """Run all generators and return deduplicated dependencies + stats."""
    stats = {
        "ontology_generated": 0,
        "pattern_generated": 0,
        "domain_generated": 0,
        "total_before_dedup": 0,
        "total_unique": 0,
        "duplicates_removed": 0,
    }

    all_deps: list[Dependency] = []

    if enable_ontology:
        onto_deps = generate_ontology_dependencies(controls)
        stats["ontology_generated"] = len(onto_deps)
        all_deps.extend(onto_deps)

    if enable_patterns:
        pat_deps = generate_pattern_dependencies(controls)
        stats["pattern_generated"] = len(pat_deps)
        all_deps.extend(pat_deps)

    if enable_domain_packs:
        dom_deps = generate_domain_dependencies(controls, domain_pack_dir)
        stats["domain_generated"] = len(dom_deps)
        all_deps.extend(dom_deps)

    stats["total_before_dedup"] = len(all_deps)

    # Deduplicate by (source, target, type)
    seen: set[tuple[str, str, str]] = set()
    unique: list[Dependency] = []
    for dep in all_deps:
        key = (dep.source_control_id, dep.target_control_id, dep.dependency_type)
        if key not in seen:
            seen.add(key)
            unique.append(dep)

    stats["total_unique"] = len(unique)
    stats["duplicates_removed"] = stats["total_before_dedup"] - stats["total_unique"]

    return unique, stats