"""cobol-bank-statement-batch-job.py - the statement and rejects that cobol-bank-statement-batch-job.cob should write.

Reads datasets/cobol-bank-statement-batch-job.dat with the copybook's layout (72-byte records: account 9(8),
date 9(8), type X, amount 9(9)V99, description X(40), filler X(4)) and applies the program's rules: the four
validity checks in the same order (account, date and amount must be all digits, the type must be D or C), a
control break on the account, and the same edited pictures (Z,ZZZ,ZZZ,ZZ9.99 for amounts, -,---,---,--9.99 with a
floating minus for balances, ZZZ,ZZ9 for counts, 9(4)/9(2)/9(2) for dates). Standard library only.

  python code/cobol-bank-statement-batch-job.py
      prints the expected statement.txt, then the expected rejects.dat (trailing spaces trimmed)
  python code/cobol-bank-statement-batch-job.py statement.txt rejects.dat
      also compares the files the COBOL program wrote with the expected lines, ignoring trailing spaces,
      prints any line that differs, and exits 1 if one does

Run it from the site folder, like the program, so the relative path to the data file resolves.
"""
import os
import sys

DAT = os.path.join("datasets", "cobol-bank-statement-batch-job.dat")


def z_amount(cents: int) -> str:
    """PIC Z,ZZZ,ZZZ,ZZ9.99: 16 characters, leading zeros suppressed, no sign."""
    return f"{abs(cents) / 100:,.2f}".rjust(16)


def floating_minus(cents: int) -> str:
    """PIC -,---,---,--9.99: 16 characters, a minus against the first digit only when negative."""
    text = f"{abs(cents) / 100:,.2f}"
    return ("-" + text if cents < 0 else text).rjust(16)


def z_count(n: int) -> str:
    """PIC ZZZ,ZZ9: 7 characters."""
    return f"{n:,}".rjust(7)


def is_numeric(s: str) -> bool:
    """The NUMERIC class test on an unsigned DISPLAY item: every character a digit."""
    return s != "" and all(c in "0123456789" for c in s)


def build(path: str = DAT):
    stmt = ["BANK STATEMENT"]
    rejects = []
    counts = {"read": 0, "accepted": 0, "rejected": 0, "accounts": 0}
    grand_dr = grand_cr = 0
    current = None
    balance = acct_dr = acct_cr = 0

    def account_break():
        stmt.append("  Debits   " + z_amount(acct_dr) + "  Credits  " + z_amount(acct_cr))
        stmt.append("  Closing balance" + " " * 48 + floating_minus(balance))

    with open(path, encoding="ascii", newline="") as f:
        for raw in f:
            rec = raw.rstrip("\r\n").ljust(72)[:72]
            counts["read"] += 1
            account, date, kind, amount, desc = rec[0:8], rec[8:16], rec[16], rec[17:28], rec[28:68]
            reason = ""
            if not is_numeric(account):
                reason = "ACCOUNT NOT NUMERIC"
            elif not is_numeric(date):
                reason = "DATE NOT NUMERIC"
            elif not is_numeric(amount):
                reason = "AMOUNT NOT NUMERIC"
            elif kind not in ("D", "C"):
                reason = "UNKNOWN TYPE"
            if reason:
                counts["rejected"] += 1
                rejects.append(rec + " | " + reason.ljust(30))
                continue
            if current != account:
                if current is not None:
                    account_break()
                current = account
                counts["accounts"] += 1
                balance = acct_dr = acct_cr = 0
                stmt.append("")
                stmt.append("Account " + account)
                stmt.append("  " + "Date".ljust(10) + "  T  " + "Description".ljust(30) + " " + "Amount".rjust(16)
                            + " " + "Balance".rjust(16))
            counts["accepted"] += 1
            cents = int(amount)
            if kind == "C":
                balance += cents
                acct_cr += cents
                grand_cr += cents
            else:
                balance -= cents
                acct_dr += cents
                grand_dr += cents
            stmt.append("  " + f"{date[0:4]}/{date[4:6]}/{date[6:8]}" + "  " + kind + "  " + desc[:30] + " "
                        + z_amount(cents) + " " + floating_minus(balance))
    if current is not None:
        account_break()
    stmt.append("")
    stmt.append("Accounts             :" + z_count(counts["accounts"]))
    stmt.append("Transactions accepted:" + z_count(counts["accepted"]))
    stmt.append("Transactions rejected:" + z_count(counts["rejected"]))
    stmt.append("Total debits         :" + z_amount(grand_dr))
    stmt.append("Total credits        :" + z_amount(grand_cr))
    return [s.rstrip() for s in stmt], [r.rstrip() for r in rejects], counts


def compare(name, expected, path) -> int:
    with open(path, encoding="ascii", errors="replace", newline="") as f:
        got = [line.rstrip("\r\n").rstrip() for line in f]
    bad = 0
    for i in range(max(len(expected), len(got))):
        e = expected[i] if i < len(expected) else "<missing>"
        g = got[i] if i < len(got) else "<missing>"
        if e != g:
            bad += 1
            print(f"{name} line {i + 1}:\n  expected {e!r}\n  got      {g!r}")
    print(f"{name}: {len(got)} lines, {bad} differ")
    return bad


def main(argv) -> int:
    stmt, rejects, counts = build()
    print("\n".join(stmt))
    print("--- rejects.dat ---")
    print("\n".join(rejects))
    print(f"--- read {counts['read']}, accepted {counts['accepted']}, rejected {counts['rejected']}, "
          f"accounts {counts['accounts']} ---")
    if len(argv) == 2:
        bad = compare("statement.txt", stmt, argv[0]) + compare("rejects.dat", rejects, argv[1])
        return 1 if bad else 0
    return 0


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))