"""NULL / missing value issues (10 issues)."""

import numpy as np
import pandas as pd
from .base import Issue, pick_rows


def _null_col(col: str, severity: str = "high", rate: float = 0.02) -> Issue:
    def inject(df, r, rng):
        df = df.copy()
        df.loc[pick_rows(df, r, rng), col] = None
        return df

    names = {
        "event_id": ("null_event_id", "Null event_id (primary key)", "critical"),
        "user_id": ("null_user_id", "Null user_id", "high"),
        "session_id": ("null_session_id", "Null session_id", "high"),
        "timestamp": ("null_timestamp", "Null event timestamp", "critical"),
        "event_type": ("null_event_type", "Null event_type", "high"),
        "page_url": ("null_page_url", "Null page URL", "medium"),
        "ip_address": ("null_ip_address", "Null IP address", "medium"),
    }
    id_, name, sev = names[col]
    return Issue(id=id_, name=name, category="nulls", description=name,
                 severity=sev, default_rate=rate, inject=inject)


def _null_revenue_purchase(df, rate, rng):
    df = df.copy()
    mask = (df["event_type"] == "purchase") & pick_rows(df, rate, rng)
    df.loc[mask, "revenue"] = None
    return df


def _null_product_purchase(df, rate, rng):
    df = df.copy()
    mask = (df["event_type"].isin(["purchase", "add_to_cart", "checkout"])) & pick_rows(df, rate, rng)
    df.loc[mask, "product_id"] = None
    return df


def _entire_row_null(df, rate, rng):
    df = df.copy()
    mask = pick_rows(df, rate, rng)
    df.loc[mask] = None
    return df


ISSUES = [
    _null_col("event_id"),
    _null_col("user_id"),
    _null_col("session_id"),
    _null_col("timestamp"),
    _null_col("event_type"),
    _null_col("page_url", severity="medium"),
    _null_col("ip_address", severity="medium"),
    Issue(
        id="null_revenue_for_purchase",
        name="Null revenue for purchase events",
        category="nulls",
        description="Revenue is null on purchase events where it is required",
        severity="high",
        default_rate=0.02,
        inject=_null_revenue_purchase,
    ),
    Issue(
        id="null_product_id_for_purchase",
        name="Null product_id for purchase/cart events",
        category="nulls",
        description="product_id is null on purchase/add_to_cart/checkout events",
        severity="high",
        default_rate=0.02,
        inject=_null_product_purchase,
    ),
    Issue(
        id="entire_row_null",
        name="Entire row null",
        category="nulls",
        description="All columns in a row are set to null",
        severity="critical",
        default_rate=0.005,
        inject=_entire_row_null,
    ),
]