"""
data_loader.py
--------------
Loads and indexes smart contract data from JSON files.

Task 1 helpers  – vulnerable function sampling
Task 2 helpers  – property function sampling, natspec, similar-rule lookup
"""

import json
import os
import random
from typing import Any, Dict, List, Optional, Tuple


DATA_DIR = os.path.join(os.path.dirname(__file__))
DEFAULT_CONTRACTS_FILE = os.path.join(DATA_DIR, "contracts.json")
DEFAULT_CSV_PATH = os.path.join(DATA_DIR, "properties.csv")


# ────────────────────────────────────────────────────────────────
# Core loaders
# ────────────────────────────────────────────────────────────────

def load_contracts(path: str = DEFAULT_CONTRACTS_FILE) -> List[Dict[str, Any]]:
    """Load and return all contracts from the JSON dataset."""
    with open(path, "r") as f:
        return json.load(f)


def get_function_by_name(
    contract: Dict[str, Any], name: str
) -> Optional[Dict[str, Any]]:
    """Case-insensitive function lookup within a contract."""
    for fn in contract.get("functions", []):
        if fn["name"].lower() == name.lower():
            return fn
    return None


def get_state_variable_by_name(
    contract: Dict[str, Any], name: str
) -> Optional[Dict[str, Any]]:
    """Case-insensitive state variable lookup."""
    for sv in contract.get("state_variables", []):
        if sv["name"].lower() == name.lower():
            return sv
    return None


def list_function_names(contract: Dict[str, Any]) -> List[str]:
    """Return all function names in the contract."""
    return [fn["name"] for fn in contract.get("functions", [])]


def list_state_variable_names(contract: Dict[str, Any]) -> List[str]:
    """Return all state variable names."""
    return [sv["name"] for sv in contract.get("state_variables", [])]


# ────────────────────────────────────────────────────────────────
# Task 1 helpers
# ────────────────────────────────────────────────────────────────

def get_all_vulnerable_entries(
    contracts: List[Dict[str, Any]],
) -> List[Tuple[Dict[str, Any], Dict[str, Any]]]:
    """
    Returns a flat list of (contract, function) pairs where
    function['vulnerable'] is True.
    """
    entries = []
    for contract in contracts:
        for fn in contract.get("functions", []):
            if fn.get("vulnerable", False):
                entries.append((contract, fn))
    return entries


def sample_episode(
    contracts: List[Dict[str, Any]],
    rng: Optional[random.Random] = None,
) -> Tuple[Dict[str, Any], Dict[str, Any]]:
    """Randomly selects one (contract, vulnerable_function) pair for Task 1."""
    if rng is None:
        rng = random.Random()
    entries = get_all_vulnerable_entries(contracts)
    if not entries:
        raise ValueError("No vulnerable functions found in dataset.")
    return rng.choice(entries)


# ────────────────────────────────────────────────────────────────
# Task 2 helpers
# ────────────────────────────────────────────────────────────────

def get_all_property_entries(
    contracts: List[Dict[str, Any]],
) -> List[Tuple[Dict[str, Any], Dict[str, Any]]]:
    """
    Returns a flat list of (contract, function) pairs where
    function['property'] is not None.
    Used by Task 2 to populate the episode pool.
    """
    entries = []
    for contract in contracts:
        for fn in contract.get("functions", []):
            if fn.get("property", None) is not None and fn.get("vulnerable", False) is False:
                entries.append((contract, fn))
    return entries


def sample_property_episode(
    contracts: List[Dict[str, Any]],
    rng: Optional[random.Random] = None,
) -> Tuple[Dict[str, Any], Dict[str, Any]]:
    """Randomly selects one (contract, function-with-property) pair for Task 2."""
    if rng is None:
        rng = random.Random()
    entries = get_all_property_entries(contracts)
    if not entries:
        raise ValueError("No functions with properties found in dataset.")
    return rng.choice(entries)


def get_related_functions(
    contract: Dict[str, Any],
    function_name: str,
) -> List[str]:
    """
    Returns function names that are related to the given function:
    - Functions that it calls (from call_graph)
    - Functions that call it (reverse call_graph lookup)
    """
    name_lower = function_name.lower()
    cg: Dict[str, List[str]] = contract.get("call_graph", {})
    related = set()

    # Direct callees (functions called by this function)
    for callee in cg.get(function_name, []):
        # Only include callees that are also functions in this contract
        if get_function_by_name(contract, callee) is not None:
            related.add(callee)

    # Reverse: functions that call this function
    for caller_name, callees in cg.items():
        if any(c.lower() == name_lower for c in callees):
            if get_function_by_name(contract, caller_name) is not None:
                related.add(caller_name)

    return sorted(related)

# ────────────────────────────────────────────────────────────────
# Task 3 helpers
# ────────────────────────────────────────────────────────────────

def get_all_task3_entries(
    contracts: List[Dict[str, Any]],
) -> List[Tuple[Dict[str, Any], Dict[str, Any]]]:
    """
    Returns (contract, function) pairs where function is vulnerable
    and has a property field.
    """
    vulnerable_entries = get_all_vulnerable_entries(contracts)
    entries = []
    for contract, fn in vulnerable_entries:
        if fn.get("property", None) is not None:
            entries.append((contract, fn))
    return entries


def sample_task3_episode(
    contracts: List[Dict[str, Any]],
    rng: Optional[random.Random] = None,
) -> Tuple[Dict[str, Any], Dict[str, Any]]:
    """Randomly selects one (contract, vulnerable_function) pair for Task 3."""
    if rng is None:
        rng = random.Random()
    entries = get_all_task3_entries(contracts)
    if not entries:
        raise ValueError("No Task 3 entries found in dataset.")
    return rng.choice(entries)