import os
import re
import time
import json
from dotenv import load_dotenv  # pyre-ignore[21]
from sqlalchemy import create_engine, text  # pyre-ignore[21]
from openai import OpenAI as OpenAIClient

load_dotenv()

# Config file paths
BASE_DIR = os.path.dirname(__file__)


def _load_json(path, name):
    try:
        with open(path, "r", encoding="utf-8") as f:
            return json.load(f)
    except (FileNotFoundError, json.JSONDecodeError) as e:
        print(f"  ✗ {name}: {e}")
        return {}


class DataBot:
    def __init__(self):
        print("Loading configurations...")
        self.db_cfg = _load_json(os.path.join(BASE_DIR, "db_config.json"), "db_config")
        self.ai_cfg = _load_json(os.path.join(BASE_DIR, "ai_config.json"), "ai_config")
        self.prompts = _load_json(os.path.join(BASE_DIR, "prompts_config.json"), "prompts_config")
        self.access_cfg = _load_json(os.path.join(BASE_DIR, "data_access_config.json"), "data_access_config")

        # Query limits
        ql = self.db_cfg.get("query_limits", {})
        self.MAX_ROWS = ql.get("max_rows", 100)
        self.MAX_QUERY_TIME = ql.get("max_query_time_seconds", 30)
        self.MAX_JOIN_TABLES = ql.get("max_join_tables", 3)

        # Pre-cache restricted columns as a lowercase set (used on every column check)
        self._restricted_cols = {c.lower() for c in self.access_cfg.get("restricted_columns", [])}

        # AI model
        self.model = self.ai_cfg.get("model", os.getenv("LLM_MODEL", "gpt-4o"))
        self.client = OpenAIClient(api_key=os.getenv("OPENAI_API_KEY"))

        # Database engine
        conn_cfg = self.db_cfg.get("connection", {})
        timeouts = self.db_cfg.get("timeouts", {})
        pool = self.db_cfg.get("pool", {})
        self.db_user = os.getenv("DB_USER")
        self.db_pass = os.getenv("DB_PASSWORD")
        self.db_host = os.getenv("DB_HOST", conn_cfg.get("host", "51.89.104.26"))
        self.db_name = os.getenv("DB_NAME", conn_cfg.get("database", "dev_poly"))
        self.port = conn_cfg.get("port", "3306")

        self.engine = create_engine(
            f"mysql+pymysql://{self.db_user}:{self.db_pass}@{self.db_host}:{self.port}/{self.db_name}?charset={conn_cfg.get('charset', 'utf8')}",
            connect_args={
                "connect_timeout": timeouts.get("connect_timeout", 30),
                "read_timeout": timeouts.get("read_timeout", 60),
                "write_timeout": timeouts.get("write_timeout", 60),
            },
            pool_pre_ping=pool.get("pool_pre_ping", True),
            pool_recycle=pool.get("pool_recycle", 300),
        )

        # Load and filter schema
        print("Loading database schema...")
        schema_cfg = self.db_cfg.get("schema_loading", {})
        raw = self._load_schema(schema_cfg.get("max_retries", 3), schema_cfg.get("retry_delay_seconds", 5))
        self.schema_info = self._filter_schema(raw)
        print(f"Loaded {len(self.schema_info)} accessible tables (from {len(raw)} total).")

    # ── Schema ────────────────────────────────────────────────────────

    def _load_schema(self, retries=3, delay=5):
        for attempt in range(1, retries + 1):
            try:
                schema = {}
                with self.engine.connect() as conn:
                    rows = conn.execute(text(
                        "SELECT TABLE_NAME, COLUMN_NAME, COLUMN_TYPE "
                        "FROM INFORMATION_SCHEMA.COLUMNS "
                        "WHERE TABLE_SCHEMA = :db ORDER BY TABLE_NAME, ORDINAL_POSITION"
                    ), {"db": self.db_name})
                    for r in rows:
                        schema.setdefault(r[0], []).append(f"{r[1]} ({r[2]})")
                return schema
            except Exception as e:
                if attempt < retries:
                    print(f"  ✗ Attempt {attempt}/{retries} failed, retrying in {delay}s...")
                    time.sleep(delay)
                else:
                    print(f"ERROR: Cannot connect to {self.db_host}:{self.port}/{self.db_name}")
                    raise SystemExit(1) from e
        return {}

    def _filter_schema(self, raw):
        if not self.access_cfg:
            return raw
        filtered = {}
        blocked = 0
        for table, cols in raw.items():
            if not self._table_allowed(table):
                blocked += 1
                continue
            safe = [c for c in cols if self._column_allowed(c.split(" (")[0].strip())]
            if safe:
                filtered[table] = safe
        if blocked:
            print(f"  → Blocked {blocked} restricted tables.")
        return filtered

    def _table_allowed(self, name):
        if not self.access_cfg:
            return True
        t = name.lower()
        for p in self.access_cfg.get("restricted_table_prefixes", []):
            if t.startswith(p.lower()):
                return False
        for p in self.access_cfg.get("allowed_table_prefixes", []):
            if t.startswith(p.lower()):
                return True
        return False

    def _column_allowed(self, name):
        if not self.access_cfg:
            return True
        return name.lower() not in self._restricted_cols

    # ── Security & Limits ─────────────────────────────────────────────

    def _validate_security(self, sql):
        if not self.access_cfg:
            return True, ""
        sql_up = sql.upper()
        for op in ("INSERT", "UPDATE", "DELETE", "DROP", "ALTER", "TRUNCATE", "CREATE"):
            if re.search(rf'\b{op}\b', sql_up):
                return False, f"Write operation '{op}' is not allowed."
        sql_lo = sql.lower()
        for prefix in self.access_cfg.get("restricted_table_prefixes", []):
            if re.search(rf'\b{re.escape(prefix.lower())}\w*\b', sql_lo):
                return False, f"Restricted data ('{prefix}*' tables). Access denied."
        for col in self.access_cfg.get("restricted_columns", []):
            if re.search(rf'\b{re.escape(col.lower())}\b', sql_lo):
                return False, f"Restricted column '{col}'. Access denied."
        return True, ""

    def _validate_complexity(self, sql):
        sql_up = sql.upper()
        if "CROSS JOIN" in sql_up:
            return False, "CROSS JOIN is not allowed."
        if len(re.findall(r'\bJOIN\b', sql_up)) > self.MAX_JOIN_TABLES:
            return False, f"Too many JOINs (max {self.MAX_JOIN_TABLES}). Simplify your question."
        if re.search(r'SELECT\s+\*', sql_up) and not re.search(r'SELECT\s+COUNT\s*\(\s*\*\s*\)', sql_up):
            return False, "SELECT * is not allowed. Specific columns must be selected."
        has_where = bool(re.search(r'\bWHERE\b', sql_up))
        has_agg = bool(re.search(r'SELECT\s+(COUNT|SUM|AVG|MIN|MAX)\s*\(', sql_up))
        has_group = bool(re.search(r'\bGROUP\s+BY\b', sql_up))
        if not has_where and not has_agg and not has_group:
            return False, "No WHERE clause or aggregation. Add filters to your question."
        return True, ""

    def _enforce_limit(self, sql):
        sql_up = sql.upper().strip()
        # Skip pure aggregates without GROUP BY
        if re.search(r'^SELECT\s+(COUNT|SUM|AVG|MIN|MAX)\s*\(', sql_up) and not re.search(r'\bGROUP\s+BY\b', sql_up):
            return sql
        m = re.search(r'\bLIMIT\s+(\d+)', sql_up)
        if m:
            if int(m.group(1)) > self.MAX_ROWS:
                sql = re.sub(r'\bLIMIT\s+\d+', f'LIMIT {self.MAX_ROWS}', sql, flags=re.IGNORECASE)
            return sql
        return f"{sql.rstrip()} LIMIT {self.MAX_ROWS}"

    # ── Prompt Helper ─────────────────────────────────────────────────

    def _prompt(self, key, **kw):
        t = self.prompts.get(key, "")
        if not t:
            print(f"  ✗ WARNING: prompt '{key}' not found in prompts_config.json")
            return ""
        try:
            return t.format(**kw)
        except KeyError as e:
            print(f"  ✗ WARNING: missing placeholder {e} in prompt '{key}'")
            return t

    # ── LLM Pipeline ─────────────────────────────────────────────────

    def _pick_tables(self, question):
        cfg = self.ai_cfg.get("table_picker", {})
        max_t = cfg.get("max_tables", 5)
        names = list(self.schema_info.keys())
        resp = self.client.chat.completions.create(
            model=self.model,
            temperature=cfg.get("temperature", 0),
            max_tokens=cfg.get("max_tokens", 200),
            messages=[
                {"role": "system", "content": self._prompt("table_picker_system")},
                {"role": "user", "content": self._prompt("table_picker_user",
                    db_name=self.db_name, table_list=", ".join(names),
                    question=question, max_tables=max_t)},
            ]
        )
        picked = [t.strip().strip("'\"` ") for t in (resp.choices[0].message.content or "").split(",")]
        valid = [t for t in picked if t in self.schema_info]
        return valid or names[:max_t]

    def _generate_sql(self, question, schema_ctx):
        cfg = self.ai_cfg.get("sql_generator", {})
        resp = self.client.chat.completions.create(
            model=self.model,
            temperature=cfg.get("temperature", 0),
            max_tokens=cfg.get("max_tokens", 500),
            messages=[
                {"role": "system", "content": self._prompt("sql_generator_system",
                    db_name=self.db_name, max_rows=self.MAX_ROWS, max_join_tables=self.MAX_JOIN_TABLES)},
                {"role": "user", "content": self._prompt("sql_generator_user",
                    schema_context=schema_ctx, question=question)},
            ]
        )
        sql = (resp.choices[0].message.content or "").strip()
        if "SECURITY_BLOCK" in sql.upper():
            return "SECURITY_BLOCK"
        if "NOT_A_QUERY" in sql.upper():
            return "NOT_A_QUERY"
        sql = sql.replace("```sql", "").replace("```", "").strip()
        if ";" in sql:
            sql = sql.split(";")[0].strip()
        return sql

    def _execute(self, sql):
        with self.engine.connect() as conn:
            # Try setting query timeout (MariaDB vs MySQL have different syntax)
            try:
                conn.execute(text(f"SET SESSION max_statement_time = {self.MAX_QUERY_TIME}"))
            except Exception:
                try:
                    conn.execute(text(f"SET SESSION MAX_EXECUTION_TIME = {self.MAX_QUERY_TIME * 1000}"))
                except Exception:
                    pass  # Neither supported — LIMIT and row cap still protect us
            result = conn.execute(text(sql))
            cols = list(result.keys())
            batch = result.fetchmany(self.MAX_ROWS + 1)
            rows = [dict(zip(cols, r)) for r in batch[:self.MAX_ROWS]]
            if len(batch) > self.MAX_ROWS:
                print(f"  → Capped at {self.MAX_ROWS} rows")
            return cols, rows

    def _summarize(self, question, sql, cols, rows):
        cfg = self.ai_cfg.get("summarizer", {})
        max_disp = cfg.get("max_display_rows", 50)
        shown = rows[:max_disp]
        result_text = f"Columns: {cols}\nRows ({len(rows)} total"
        if len(rows) > max_disp:
            result_text += f", showing first {max_disp}"
        result_text += "):\n" + "\n".join(str(r) for r in shown)

        resp = self.client.chat.completions.create(
            model=self.model,
            temperature=cfg.get("temperature", 0.3),
            max_tokens=cfg.get("max_tokens", 2000),
            messages=[
                {"role": "system", "content": self._prompt("summarizer_system", db_name=self.db_name)},
                {"role": "user", "content": self._prompt("summarizer_user",
                    question=question, sql=sql, result_text=result_text)},
            ]
        )
        return (resp.choices[0].message.content or "").strip()

    # ── Main Entry ────────────────────────────────────────────────────

    def ask(self, question):
        try:
            tables = self._pick_tables(question)
            print(f"  → Tables: {', '.join(tables)}")

            schema_ctx = "\n".join(
                f"Table '{t}': {', '.join(self.schema_info[t])}"
                for t in tables if t in self.schema_info
            )

            sql = self._generate_sql(question, schema_ctx)

            responses = self.prompts.get("responses", {})
            if sql == "NOT_A_QUERY":
                return responses.get("not_a_query", "I'm DataBot. Ask me about your business data.")
            if sql == "SECURITY_BLOCK":
                return responses.get("security_block", "Access denied: sensitive data requested.")

            print(f"  → SQL: {sql}")

            ok, reason = self._validate_security(sql)
            if not ok:
                print(f"  → BLOCKED: {reason}")
                return responses.get("security_check_fail", "Query blocked: {reason}").format(reason=reason)

            ok, reason = self._validate_complexity(sql)
            if not ok:
                print(f"  → BLOCKED: {reason}")
                return responses.get("complexity_fail", "Query too complex: {reason}").format(reason=reason)

            sql = self._enforce_limit(sql)
            print(f"  → Final: {sql}")

            cols, rows = self._execute(sql)
            return self._summarize(question, sql, cols, rows)

        except Exception as e:
            return f"DataBot Error: {str(e)}"