import math

EPD_REASON_MAP = {
    "000": "No Adverse Factors",
    "001": "Available Credit On Bankcard Accounts Is Too Low",
    "006": "Bankcard Account Balances Are Too High In Proportion To Credit Limits",
    "010": "Too Many Delinquencies",
    "016": "Too Few Satisfactory Accounts",
    "020": "Length Of Time Revolving Accounts Have Been Established Is Too Short",
    "022": "Too many inquiries",
    "023": "Months Since Most Recent Delinquency Is Too Short",
    "024": "Too Many Serious Delinquencies",
    "026": "Number Of Delinquent Accounts Is Too High In Proportion To Total Number Of Accounts",
    "029": "Retail Account Balances Are Too High In Proportion To Credit Limits",
    "030": "Not Enough Retail Debt Experience",
    "031": "Revolving Account Balances Are Too High In Proportion To Credit Limits",
    "035": "Length Of Time Accounts Have Been Established Is Too Short",
    "037": "Too Few Bankcard Accounts",
    "043": "Too Few Open Revolving Accounts",
    "061": "Too Many Recently Opened Accounts",
    "066": "Too Many Serious Derogatory Items",
    "069": "Not Enough Debt Experience",
    "070": "Length Of Time Since Most Recent Bankcard Account Has Been Established Is Too Short",
    "074": "Too Few Satisfactory Revolving Accounts",
    "076": "Total Amount Past Due Is Too High",
    "103": "Not Enough Available Credit",
    "105": "Too Few Revolving Accounts",
    "117": "Length Of Time Since Most Seriously Delinquent Account Has Been Established Is Too Short",
    "132": "Too Few Open Accounts",
    "142": "Not Enough Balance Decreases On Active Non-Mortgage Accounts",
    "146": "Recency Of A Balance Overlimit On A Bankcard Account",
    "154": "Insufficient Payment Activity Over The Last Year",
    "155": "Recency Of Max Aggregate Bankcard Balance Over The Last Year",
    "158": "Too Few Open Retail Accounts",
    "174": "Too Few Open Bankcard Accounts",
    "181": "High Recent Balance Range Relative To Previous Balance Range",
    "192": "Not Enough Available Credit On Revolving Accounts",
    "201": "Length Of Time Since Oldest Auto Account Has Been Established Is Too Short"
}

VANTAGE_REASON_MAP = {
    "10": "Too few accounts paid as agreed",
    "11": "Oldest account was opened too recently",
    "12": "Delinquent or derogatory status on accounts is too recent",
    "13": "Balances on delinquent or derogatory accounts are too high",
    "14": "Too high proportion of accounts recently opened",
    "15": "Lack of recently reported accounts",
    "16": "Total of credit limits and loan amounts is too low",
    "17": "No open accounts in your credit file",
    "18": "Lack of account information",
    "19": "No negative reason code",
    "20": "Delinquent or derogatory bankcard",
    "21": "Too many bankcards with a high balance",
    "22": "Too few bankcards with high credit limit",
    "23": "Too high proportion of bankcards recently opened",
    "24": "Too many bankcards with high balance compared to credit limit",
    "25": "Too high proportion of balances from bankcards",
    "26": "Balances on bankcards are too high",
    "27": "Delinquent or derogatory status on revolving accounts is too recent",
    "28": "Average credit limit on open bankcards is too low",
    "29": "Balances on bankcards are too high compared with credit limits",
    "30": "Too few open revolving accounts",
    "31": "Not enough available credit on revolving accounts",
    "32": "Oldest bankcard was opened too recently",
    "33": "Not enough balance paid down over time on bankcards",
    "34": "Most recently opened revolving account is too new",
    "35": "Lack of revolving account information",
    "36": "Lack of recently reported revolving accounts",
    "37": "No open bankcards in your credit file",
    "38": "Lack of bankcard account information",
    "39": "Balances on delinquent or derogatory bankcards are too high",
    "4": "Balances on accts too high compared to credit limits and loan amounts",
    "04": "Balances on accts too high compared to credit limits and loan amounts",
    "40": "Too many delinquent or derogatory revolving accounts",
    "41": "Average time since revolving accounts opened is too recent",
    "42": "Total credit limits on open revolving accounts are too low",
    "43": "Too many revolving accounts with high balance compared to credit limit",
    "44": "Balances on revolving accts are too high compared with credit limits",
    "45": "Not enough balance paid down over time on retail accounts",
    "46": "Oldest revolving account was opened too recently",
    "47": "No open retail accounts in your credit file",
    "48": "Lack of retail account information",
    "49": "Not enough balance paid down over time on revolving accounts",
    "5": "Too many recent delinquencies",
    "05": "Too many recent delinquencies",
    "50": "Balances on personal installment accts too high compared to loan amts",
    "51": "Too few installment accounts recently paid as agreed",
    "52": "Delinquent or derogatory installment account",
    "53": "Not enough balance paid down over time on installment accounts",
    "54": "Delinquent or derogatory status on installment accounts is too recent",
    "55": "Lack of recently reported auto accounts",
    "56": "Lack of recently reported installment accounts",
    "57": "No open installment accounts in your credit file",
    "58": "Lack of installment account information",
    "59": "Balances on retail cards are too high compared with credit limits",
    "6": "Too many accounts recently opened",
    "06": "Too many accounts recently opened",
    "60": "Total delinquent or derogatory balances on real estate loans too high",
    "61": "No open first mortgage accounts in your credit file",
    "62": "Lack of first mortgage account information",
    "63": "Delinquent or derogatory real estate secured loan",
    "64": "Not enough balance paid down over time on real estate secured loans",
    "65": "Oldest real estate secured loan was opened too recently",
    "66": "Delinquent or derogatory status on real estate loans is too recent",
    "67": "No open real estate secured loans in your credit file",
    "68": "Lack of real estate secured loan information",
    "69": "Too high proportion of balances from loans not secured by real estate",
    "7": "You have too many delinquent or derogatory accounts",
    "07": "You have too many delinquent or derogatory accounts",
    "70": "Too high proportion of auto accounts are delinquent or derogatory",
    "71": "Not enough balance paid down over time on auto accounts",
    "72": "Too few auto accounts paid as agreed",
    "73": "Delinquent or derogatory auto account",
    "74": "Balances on auto accounts are too high compared with loan amounts",
    "75": "Payments on auto accounts less than scheduled amount",
    "76": "Delinquent or derogatory status on auto accounts is too recent",
    "77": "No open auto accounts in your credit file",
    "78": "Lack of auto account information",
    "79": "No negative reason code",
    "8": "Too few accounts recently paid as agreed",
    "08": "Too few accounts recently paid as agreed",
    "80": "Delinquent or derogatory student loan",
    "81": "Not enough balance paid down over time on student loans",
    "82": "Lack of recently reported student loans",
    "83": "No negative reason code",
    "84": "Number of inquiries was a factor in determining the score",
    "85": "Too many inquiries",
    "86": "Derogatory public records",
    "87": "Unpaid collections",
    "88": "Bankruptcy",
    "89": "No negative reason code",
    "9": "Delinquent or derogatory account",
    "09": "Delinquent or derogatory account",
    "90": "No open revolving accounts in your credit file",
    "91": "Balances on delinquent or derogatory revolving accounts are too high",
    "92": "Delinquent or derogatory first mortgage",
    "93": "Not enough balance paid down over time on first mortgage accounts",
    "94": "No negative reason code",
    "95": "No negative reason code",
    "96": "Too few open accounts",
    "97": "Too few accounts"
}

REASON_MAP = {
    'evtg04':   "System Generated",
    'eads66':   "System Generated",
    's004s':    "Length of time on file is too short",
    'mt34s':    "Not enough balance decreases on mortgage trades in the past 12 months",
    'ct320':    "Insufficient payment activity",
    'us21s':    "Length of time since most recent installment account has been established is too short",
    'utlmag02': "Revolving account balances are too high in proportion to credit limits over the last 24 months",
    'trv01':    "Recency of a balance overlimit on a bankcard account",
    'us34s':    "Not enough balance decreases on installment trades in the past 12 months"
}


def generate_reason_codes(score_key, factors):
    # fallback to 4 null rows if no factors found
    if not isinstance(factors, list) or len(factors) == 0:
        return [{"code": None, "rank": None, "description": None} for _ in range(4)]

    reason_map = VANTAGE_REASON_MAP if score_key == "evtg04" else EPD_REASON_MAP if score_key == "eads66" else {}

    reason_codes = []
    for f in factors[:4]:
        code = f.get("code")
        rank = f.get("rank")
        description = reason_map.get(str(code), "")
        reason_codes.append({
            "code": code,
            "rank": rank,
            "description": description
        })

    # pad to 4
    while len(reason_codes) < 4:
        reason_codes.append({"code": None, "rank": None, "description": None})

    return reason_codes


def post_processing(processing_output, record):
    prediction = processing_output["prediction"]
    shape_reasoncode = processing_output["shape_reasoncode"]

    # grade mapping:
    if prediction < 0:
        grade = "M14"
    else:
        m = math.ceil(prediction / 0.01)
        m = max(m, 1)
        m = min(m, 14)
        grade = f"M{m}"

    # if prediction ≤ 0.04, not declined
    if prediction <= 0.04:
        return {
            "grade": grade,
            "reason_codes": [{
                "code": None,
                "rank": None,
                "description": None
            }]
        }

    conditions = {
        'evtg04': lambda x: x < 700,
        'eads66': lambda x: x < 700,
        's004s': lambda x: x < 12,
        'mt34s': lambda x: x > 95,
        'ct320': lambda x: x <= 3,
        'us21s': lambda x: x <= 3,
        'utlmag02': lambda x: x > 300,
        'trv01': lambda x: x <= 3,
        'us34s': lambda x: x > 90
    }

    for item in shape_reasoncode:
        feat = item.get("feature")
        val = item.get("value")
        cond = conditions.get(feat)

        if cond:
            try:
                if cond(val):
                    # If score-type feature (evtg04 or eads66) → full factors-based reason
                    if feat in ("evtg04", "eads66"):
                        return {
                            "grade": grade,
                            "reason_codes": generate_reason_codes(feat, record.get(f"{feat}_factors", []))
                        }
                    else:
                        # Other features → only 1 reason code based on REASON_MAP
                        return {
                            "grade": grade,
                            "reason_codes": [{
                                "code": feat,
                                "rank": "1",
                                "description": REASON_MAP.get(feat, "Reason not mapped")
                            }]
                        }
            except Exception:
                continue

    # Default fallback
    return {
        "grade": grade,
        "reason_codes": [{
            "code": feat,
            "rank": "1",
            "description": "No suitable Product Offerings found"
        }]
    }