# app/pipeline.py
import os
import json
import logging
import re
from typing import Any, Dict, List, Optional, Tuple

import pandas as pd
import numpy as np

logger = logging.getLogger("pipeline")
logger.setLevel(logging.INFO)

# ---------------------------
# Safety / helpers
# ---------------------------

DISALLOWED_PATTERNS = [
    r"__\w+__", r"\bimport\s+os\b", r"\bimport\s+sys\b", r"\bimport\s+subprocess\b",
    r"\bimport\s+socket\b", r"\bimport\s+requests\b", r"\bopen\s*\(", r"\beval\s*\(",
    r"\bexec\s*\(", r"\bcompile\s*\(", r"\bsystem\s*\(", r"\bPopen\b", r"\bsh\b",
]

def code_is_safe(code: str) -> Tuple[bool, Optional[str]]:
    for pat in DISALLOWED_PATTERNS:
        if re.search(pat, code):
            return False, f"disallowed pattern: {pat}"
    return True, None

def to_json_serializable(obj):
    if isinstance(obj, (np.integer,)):
        return int(obj)
    if isinstance(obj, (np.floating,)):
        return float(obj)
    if isinstance(obj, (np.ndarray,)):
        return obj.tolist()
    if pd.isna(obj):
        return None
    return obj

def simple_schema(df: pd.DataFrame) -> Dict[str, Any]:
    return {
        "columns": [
            {"name": c, "dtype": str(df[c].dtype), "n_unique": int(df[c].nunique(dropna=True))}
            for c in df.columns
        ],
        "n_rows": int(len(df)),
    }

# ---------------------------
# Ingest / preprocess / sampling
# ---------------------------

def ingest_file(path: str, sheet: Optional[str] = None) -> Tuple[pd.DataFrame, Dict[str, Any]]:
    ext = os.path.splitext(path)[1].lower()
    metadata = {"file_type": ext, "sheet_names": None, "selected_sheet": None}
    if ext in [".csv", ".txt"]:
        df = pd.read_csv(path)
        metadata["selected_sheet"] = "csv"
    elif ext in [".xls", ".xlsx"]:
        xls = pd.ExcelFile(path)
        sheets = xls.sheet_names
        metadata["sheet_names"] = sheets
        chosen = sheet if sheet and sheet in sheets else sheets[0]
        metadata["selected_sheet"] = chosen
        df = pd.read_excel(xls, sheet_name=chosen)
    else:
        raise ValueError("Unsupported file type: " + ext)
    metadata["file_type"] = ext
    return df, metadata

def preprocess_df(df: pd.DataFrame) -> Tuple[pd.DataFrame, Dict[str, Any]]:
    actions = []
    df = df.copy()
    df.columns = [str(c).strip() for c in df.columns]

    object_cols = df.select_dtypes(include="object").columns.tolist()
    for c in object_cols:
        try:
            df[c] = df[c].where(df[c].isna(), df[c].astype(str).str.strip())
        except Exception:
            pass

    for c in df.columns:
        if df[c].dtype == object:
            coerced = pd.to_numeric(df[c], errors="coerce")
            non_na = coerced.notna().sum()
            if non_na >= max(1, 0.5 * len(df)):
                df[c] = coerced
                actions.append(f"coerced {c} -> numeric")

    num_cols = df.select_dtypes(include=[np.number]).columns.tolist()
    for c in num_cols:
        median = df[c].median()
        if pd.isna(median):
            median = 0
        df[c] = df[c].fillna(median)
        actions.append(f"filled numeric {c} nulls with median {median}")

    for c in object_cols:
        try:
            mode = df[c].mode().iloc[0] if not df[c].mode().empty else ""
        except Exception:
            mode = ""
        df[c] = df[c].fillna(mode)
        actions.append(f"filled object {c} nulls with mode '{mode}'")

    schema = simple_schema(df)
    return df, {"actions": actions, "schema": schema}

def sample_df(df: pd.DataFrame, n: int = 5) -> Dict[str, Any]:
    head = df.head(n).to_dict(orient="records")
    tail = df.tail(n).to_dict(orient="records")
    rnd = df.sample(n=n, random_state=42).to_dict(orient="records") if len(df) > n else df.sample(frac=1.0).to_dict(orient="records")
    return {"head": head, "tail": tail, "random": rnd}

# ---------------------------
# Deterministic chart generator (fallback)
# ---------------------------

def _pick_categorical(df: pd.DataFrame) -> Optional[str]:
    for c in df.columns:
        if df[c].dtype == object or df[c].nunique() < max(50, 0.5 * len(df)):
            return c
    return None

def _pick_numeric(df: pd.DataFrame, exclude: List[str] = []) -> Optional[str]:
    for c in df.select_dtypes(include=[np.number]).columns:
        if c not in exclude:
            return c
    for c in df.columns:
        try:
            coerced = pd.to_numeric(df[c], errors="coerce")
            if coerced.notna().sum() > 0:
                return c
        except Exception:
            continue
    return None

def _pick_datetime_or_index(df: pd.DataFrame) -> Optional[str]:
    for c in df.columns:
        if np.issubdtype(df[c].dtype, np.datetime64):
            return c
    for c in df.columns:
        try:
            parsed = pd.to_datetime(df[c], errors="coerce")
            if parsed.notna().sum() > 0:
                return c
        except Exception:
            continue
    return None

def _box_aggregate(df: pd.DataFrame, cat_col: Optional[str], num_col: str) -> List[Dict[str, Any]]:
    out = []
    if cat_col is None:
        series = df[num_col].dropna()
        if len(series) == 0:
            return out
        q1 = float(series.quantile(0.25))
        median = float(series.quantile(0.5))
        q3 = float(series.quantile(0.75))
        out.append({"category": None, "q1": q1, "median": median, "q3": q3})
        return out
    for name, group in df.groupby(cat_col):
        ser = group[num_col].dropna()
        if len(ser) == 0:
            continue
        q1 = float(ser.quantile(0.25))
        median = float(ser.quantile(0.5))
        q3 = float(ser.quantile(0.75))
        out.append({"category": to_json_serializable(name), "q1": q1, "median": median, "q3": q3})
    return out

def generate_chart_data_from_spec(df: pd.DataFrame, spec: Dict[str, Any]) -> Tuple[str, List[Dict[str, Any]]]:
    chart_type = spec.get("chart_type")
    cols = spec.get("target_columns", [])
    agg = spec.get("aggregation", None)
    df_local = df.copy()

    if chart_type == "pie":
        if len(cols) == 0:
            col = _pick_categorical(df_local)
            cols = [col] if col else []
        if len(cols) == 1:
            col = cols[0]
            series = df_local[col].astype(str).value_counts(dropna=True)
            return "pie", [{"name": k, "value": int(v)} for k, v in series.items()]
        else:
            cat, val = cols[0], cols[1]
            grouped = df_local.groupby(cat)[val].sum().reset_index()
            return "pie", [{"name": r[cat], "value": to_json_serializable(r[val])} for r in grouped.to_dict(orient="records")]

    if chart_type == "bar":
        if len(cols) == 0:
            label = _pick_categorical(df_local)
            cols = [label] if label else []
        if len(cols) == 1:
            label = cols[0]
            series = df_local[label].astype(str).value_counts().reset_index()
            series.columns = [label, "count"]
            return "bar", [{"label": r[label], "count": int(r["count"])} for r in series.to_dict(orient="records")]
        else:
            label, metric = cols[0], cols[1]
            if agg in (None, "", "sum"):
                grouped = df_local.groupby(label)[metric].sum().reset_index()
            elif agg == "mean":
                grouped = df_local.groupby(label)[metric].mean().reset_index()
            else:
                grouped = df_local.groupby(label)[metric].sum().reset_index()
            return "bar", [{"label": r[label], metric: to_json_serializable(r[metric])} for r in grouped.to_dict(orient="records")]

    if chart_type == "line":
        if len(cols) < 2:
            y = _pick_numeric(df_local)
            x = _pick_datetime_or_index(df_local)
            cols = [x, y]
        xcol, ycol = cols[0], cols[1]
        s_x = pd.to_datetime(df_local[xcol], errors="coerce") if xcol in df_local.columns else pd.Series(range(len(df_local)))
        series = pd.DataFrame({"x": s_x, "y": df_local[ycol]})
        try:
            series = series.sort_values("x").reset_index(drop=True)
        except Exception:
            pass
        out = []
        for r in series.to_dict(orient="records"):
            x_val = r["x"].isoformat() if hasattr(r["x"], "isoformat") else r["x"]
            out.append({"x": to_json_serializable(x_val), "y": to_json_serializable(r["y"])})
        return "line", out

    if chart_type == "scatter":
        if len(cols) < 2:
            x = _pick_numeric(df_local)
            y = _pick_numeric(df_local, exclude=[x]) if x else None
            cols = [x, y]
        xcol, ycol = cols[0], cols[1]
        return "scatter", [{"x": to_json_serializable(r[xcol]), "y": to_json_serializable(r[ycol])} for r in df_local[[xcol, ycol]].to_dict(orient="records")]

    if chart_type == "histogram":
        col = cols[0] if cols else _pick_numeric(df_local)
        series = df_local[col].dropna()
        counts, bin_edges = np.histogram(series, bins=10)
        out = []
        for i in range(len(counts)):
            out.append({"bin": f"{float(bin_edges[i]):.6g}-{float(bin_edges[i+1]):.6g}", "count": int(counts[i])})
        return "histogram", out

    if chart_type == "boxplot":
        if len(cols) == 0:
            num = _pick_numeric(df_local)
            return "boxplot", _box_aggregate(df_local, None, num)
        if len(cols) == 1:
            num = cols[0]
            return "boxplot", _box_aggregate(df_local, None, num)
        cat, num = cols[0], cols[1]
        return "boxplot", _box_aggregate(df_local, cat, num)

    return chart_type or "unknown", []

# ---------------------------
# Gemini wrapper (optional)
# ---------------------------

def gemini_generate_json(model: str, system_instruction: str, user_content: str, require_json: bool = True) -> Any:
    """
    Attempts to call google-genai if GEMINI_API_KEY is provided.
    Falls back to returning a safe marker that indicates a deterministic fallback should be used.
    """
    api_key = "AIzaSyDfy0E-9b2XjoYHrHX2C1nVLHWyrWUFkMs"
    if not api_key:
        logger.info("GEMINI_API_KEY not set; using deterministic fallbacks.")
        return {"__use_fallback__": True}

    try:
        # import lazily
        from google import genai
        from google.genai import types
    except Exception as e:
        logger.exception("google-genai not available: %s", e)
        return {"__use_fallback__": True}

    client = genai.Client(api_key=api_key)
    contents = [
        types.Content(
            role="user",
            parts=[types.Part.from_text(text=user_content)],
        )
    ]
    config = types.GenerateContentConfig(
        thinking_config=types.ThinkingConfig(thinking_budget=0),
        response_mime_type="application/json",
        system_instruction=[types.Part.from_text(text=system_instruction)],
    )
    full_text = ""
    try:
        for chunk in client.models.generate_content_stream(model=model, contents=contents, config=config):
            if hasattr(chunk, "text") and chunk.text:
                full_text += chunk.text
            elif (
                chunk.candidates
                and chunk.candidates[0].content
                and chunk.candidates[0].content.parts
                and chunk.candidates[0].content.parts[0].text
            ):
                full_text += chunk.candidates[0].content.parts[0].text
        full_text = full_text.strip()
        if require_json:
            try:
                return json.loads(full_text)
            except Exception:
                return {"__raw_text__": full_text}
        return full_text
    except Exception as e:
        logger.exception("genai call failed: %s", e)
        return {"__use_fallback__": True}

# ---------------------------
# Controller
# ---------------------------

DEFAULT_MODEL = "gemini-2.5-flash-lite"

def ensure_six_tasks(tasks: List[Dict[str, Any]], df: pd.DataFrame) -> List[Dict[str, Any]]:
    existing_types = [t.get("chart_type") for t in tasks]
    candidates = ["pie", "bar", "line", "scatter", "histogram", "boxplot"]
    out = tasks[:]
    for ct in candidates:
        if len(out) >= 6:
            break
        if ct not in existing_types:
            if ct == "pie":
                col = _pick_categorical(df) or df.columns[0]
                out.append({"chart_type": "pie", "target_columns": [col], "aggregation": "count", "reasoning": "fallback pie"})
            elif ct == "bar":
                label = _pick_categorical(df) or df.columns[0]
                num = _pick_numeric(df) or df.columns[0]
                out.append({"chart_type": "bar", "target_columns": [label, num], "aggregation": "sum", "reasoning": "fallback bar"})
            elif ct == "line":
                y = _pick_numeric(df) or df.columns[0]
                x = _pick_datetime_or_index(df) or df.index.name or "index"
                if x == "index":
                    out.append({"chart_type": "line", "target_columns": [x, y], "aggregation": None, "reasoning": "fallback line on index"})
                else:
                    out.append({"chart_type": "line", "target_columns": [x, y], "aggregation": None, "reasoning": "fallback line"})
            elif ct == "scatter":
                x = _pick_numeric(df)
                y = _pick_numeric(df, exclude=[x]) or x
                out.append({"chart_type": "scatter", "target_columns": [x, y], "aggregation": None, "reasoning": "fallback scatter"})
            elif ct == "histogram":
                num = _pick_numeric(df) or df.columns[0]
                out.append({"chart_type": "histogram", "target_columns": [num], "aggregation": None, "reasoning": "fallback histogram"})
            elif ct == "boxplot":
                num = _pick_numeric(df) or df.columns[0]
                cat = _pick_categorical(df)
                if cat:
                    out.append({"chart_type": "boxplot", "target_columns": [cat, num], "aggregation": None, "reasoning": "fallback boxplot by category"})
                else:
                    out.append({"chart_type": "boxplot", "target_columns": [num], "aggregation": None, "reasoning": "fallback boxplot global"})
    return out

def process_file(path: str, sheet: Optional[str] = None, model: str = DEFAULT_MODEL) -> Dict[str, Any]:
    df, meta = ingest_file(path, sheet)
    pre_df, preprocess_meta = preprocess_df(df)
    samples = sample_df(pre_df, n=5)

    classification_input = json.dumps({"samples": samples, "schema": simple_schema(pre_df), "meta": meta})
    classification_output = gemini_generate_json(
        model=model,
        system_instruction="You are a classification agent. Identify domain and chart tasks.",
        user_content=classification_input,
        require_json=True,
    )

    if not isinstance(classification_output, dict) or "tasks" not in classification_output:
        fallback = {
            "domain": "unknown",
            "tasks": [
                {"chart_type": "pie", "target_columns": [_pick_categorical(pre_df) or pre_df.columns[0]], "aggregation": "count", "reasoning": "fallback"},
                {"chart_type": "bar", "target_columns": [_pick_categorical(pre_df) or pre_df.columns[0], _pick_numeric(pre_df) or pre_df.columns[0]], "aggregation": "sum", "reasoning": "fallback"},
            ],
        }
        classification_output = fallback

    planning_input = json.dumps({"classification": classification_output, "schema": simple_schema(pre_df), "samples": samples})
    planning_output = gemini_generate_json(
        model=model,
        system_instruction="You are a planning agent. Produce tasks with code assigning `result` variable.",
        user_content=planning_input,
        require_json=True,
    )

    tasks = []
    if isinstance(planning_output, dict) and "tasks" in planning_output:
        tasks = planning_output["tasks"]
    else:
        tasks = classification_output.get("tasks", [])

    tasks = ensure_six_tasks(tasks, pre_df)

    final = {"pie": [], "bar": [], "line": [], "scatter": [], "histogram": [], "boxplot": []}
    execution_errors = []

    for idx, task in enumerate(tasks):
        chart_type = task.get("chart_type")
        code_snippet = task.get("code")
        executed = False

        if code_snippet:
            safe, reason = code_is_safe(code_snippet)
            if not safe:
                logger.warning("Rejected unsafe code snippet: %s", reason)
            else:
                allowed_globals = {
                    "__builtins__": {"None": None, "True": True, "False": False, "len": len, "min": min, "max": max, "sum": sum, "sorted": sorted, "round": round},
                    "pd": pd, "np": np, "df": pre_df.copy(),
                }
                local_vars = {}
                try:
                    exec(code_snippet, allowed_globals, local_vars)
                    result = None
                    if "result" in local_vars:
                        result = local_vars["result"]
                    elif "output" in local_vars:
                        result = local_vars["output"]
                    else:
                        single_expr = (("\n" not in code_snippet) and ("=" not in code_snippet) and ("return" not in code_snippet) and (not code_snippet.strip().startswith("def ")))
                        if single_expr:
                            try:
                                result = eval(code_snippet, allowed_globals, {})
                            except Exception:
                                result = None

                    result_json = None
                    if isinstance(result, pd.DataFrame):
                        result_json = [{k: to_json_serializable(v) for k, v in r.items()} for r in result.to_dict(orient="records")]
                    elif isinstance(result, list):
                        norm = []
                        for r in result:
                            if isinstance(r, dict):
                                norm.append({k: to_json_serializable(v) for k, v in r.items()})
                            else:
                                norm.append(to_json_serializable(r))
                        result_json = norm
                    elif isinstance(result, dict):
                        result_json = [{k: to_json_serializable(v) for k, v in result.items()}]
                    else:
                        result_json = None

                    if result_json is not None:
                        normalized = []
                        for item in result_json:
                            if isinstance(item, dict):
                                normalized.append(item)
                            else:
                                normalized.append({"value": to_json_serializable(item)})
                        if chart_type in final:
                            final[chart_type].extend(normalized)
                        else:
                            final.setdefault(chart_type, []).extend(normalized)
                        executed = True

                    if not executed:
                        execution_errors.append({"task_index": idx, "reason": "result not list-of-dicts or missing", "code": code_snippet})
                except Exception as e:
                    logger.exception("Model code execution failed for task %s: %s", idx, str(e))
                    execution_errors.append({"task_index": idx, "reason": "exception during exec/eval", "exception": str(e), "code": code_snippet})

        if not executed:
            ct, res = generate_chart_data_from_spec(pre_df, task)
            final.setdefault(ct, []).extend(res)

    for k in final:
        if isinstance(final[k], list):
            final[k] = final[k][:200]

    output_payload = {
        "metadata": {
            "source_file": os.path.basename(path),
            "ingestion_meta": meta,
            "preprocess_meta": preprocess_meta,
            "classification": classification_output if isinstance(classification_output, dict) else {"raw": classification_output},
            "planning_meta": planning_output if isinstance(planning_output, dict) else {"raw": planning_output},
            "execution_errors": execution_errors,
        },
        "charts": final,
    }
    return output_payload