#!/usr/bin/env python3
"""
Convert PACK_CONTAFIN.pck from Oracle 21c (FORALL/BULK) to Oracle 10g compatible syntax.

Replaces 3 FORALL blocks in SCRIE_JC_2007 with equivalent FOR LOOPs:
  T1: FORALL UPDATE  -> FOR LOOP UPDATE
  T2: FOR + SQL%BULK_ROWCOUNT -> inline SQL%ROWCOUNT (folds into T1's loop)
  T3: FORALL INSERT  -> FOR LOOP INSERT
  T4: add END LOOP after last INSERT value
  T5: FORALL DELETE  -> FOR LOOP DELETE
  T6: add END LOOP after last DELETE condition

Exit codes: 0=ok, 1=validation failed, 2=IO error

---------------------------------------------------------------------------
UTILIZARE / USAGE
---------------------------------------------------------------------------

Linux / WSL:
  python3 scripts/convert_to_10g.py                  # conversie normala
  python3 scripts/convert_to_10g.py --dry-run         # doar arata diff, nu scrie
  python3 scripts/convert_to_10g.py --no-backup       # fara fisier .bak
  python3 scripts/convert_to_10g.py --input alt.pck --output out.pck

Windows (din radacina proiectului):
  scripts\\convert_to_10g.bat
  scripts\\convert_to_10g.bat --dry-run
  scripts\\convert_to_10g.bat --input alt.pck --output out.pck

Argumente optionale:
  --dry-run      Afiseaza diff-ul fara sa scrie nimic pe disk
  --no-backup    Nu crea fisierul <output>.bak inainte de scriere
  --input FILE   Fisier sursa  (default: input/PACK_CONTAFIN.pck)
  --output FILE  Fisier destinatie (default: input/PACK_CONTAFIN_ORACLE_10G.pck)
---------------------------------------------------------------------------
"""

import argparse
import difflib
import os
import sys
import tempfile

# ---------------------------------------------------------------------------
# Transformations (exact string, \n normalized — CRLF handled at I/O layer)
# ---------------------------------------------------------------------------

TRANSFORMS = [
    {
        "id": "T1",
        "desc": "FORALL UPDATE -> FOR LOOP UPDATE",
        "old": (
            "      -- BULK UPDATE all rows at once using FORALL\n"
            "      FORALL i IN 1 .. S.COUNT\n"
            "        UPDATE JC2007 J"
        ),
        "new": (
            "      -- UPDATE all rows using FOR loop (Oracle 10g compatible)\n"
            "      FOR i IN 1 .. S.COUNT LOOP\n"
            "        UPDATE JC2007 J"
        ),
        "expected_count": 1,
    },
    {
        "id": "T2",
        "desc": "FOR + SQL%BULK_ROWCOUNT -> inline SQL%ROWCOUNT",
        "old": (
            "           AND NVL(J.ID_SUCURSALA, -99) = NVL(S(i).ID_SUCURSALA, -99);\n"
            "\n"
            "      -- Populate SI and SD collections for INSERT and DELETE\n"
            "      FOR i IN 1 .. S.COUNT LOOP\n"
            "        IF SQL%BULK_ROWCOUNT(i) = 0 THEN"
        ),
        "new": (
            "           AND NVL(J.ID_SUCURSALA, -99) = NVL(S(i).ID_SUCURSALA, -99);\n"
            "\n"
            "        -- Check result of UPDATE and populate SI/SD collections\n"
            "        IF SQL%ROWCOUNT = 0 THEN"
        ),
        "expected_count": 1,
    },
    {
        "id": "T3",
        "desc": "FORALL INSERT -> FOR LOOP INSERT",
        "old": (
            "      -- BULK INSERT for new rows\n"
            "      IF SI.COUNT > 0 THEN\n"
            "        FORALL i IN 1 .. SI.COUNT\n"
            "          INSERT INTO JC2007"
        ),
        "new": (
            "      -- INSERT for new rows (Oracle 10g compatible)\n"
            "      IF SI.COUNT > 0 THEN\n"
            "        FOR i IN 1 .. SI.COUNT LOOP\n"
            "          INSERT INTO JC2007"
        ),
        "expected_count": 1,
    },
    {
        "id": "T4",
        "desc": "Add END LOOP after last INSERT value",
        "old": (
            "             SI(i).ID_SUCURSALA);\n"
            "      END IF;\n"
            "\n"
            "      -- BULK DELETE for rows where all values became 0 after UPDATE"
        ),
        "new": (
            "             SI(i).ID_SUCURSALA);\n"
            "        END LOOP;\n"
            "      END IF;\n"
            "\n"
            "      -- DELETE for rows where all values became 0 after UPDATE (Oracle 10g compatible)"
        ),
        "expected_count": 1,
    },
    {
        "id": "T5",
        "desc": "FORALL DELETE -> FOR LOOP DELETE",
        "old": (
            "        FORALL i IN 1 .. SD.COUNT\n"
            "          DELETE FROM JC2007 J"
        ),
        "new": (
            "        FOR i IN 1 .. SD.COUNT LOOP\n"
            "          DELETE FROM JC2007 J"
        ),
        "expected_count": 1,
    },
    {
        "id": "T6",
        "desc": "Add END LOOP after last DELETE condition",
        "old": (
            "             AND J.ROTN100 = 0;\n"
            "      END IF;"
        ),
        "new": (
            "             AND J.ROTN100 = 0;\n"
            "        END LOOP;\n"
            "      END IF;"
        ),
        "expected_count": 1,
    },
]


# ---------------------------------------------------------------------------
# I/O helpers
# ---------------------------------------------------------------------------

def load_file(path):
    """Load file, detect CRLF, return (text_with_LF, used_crlf, encoding_used)."""
    for enc in ("utf-8-sig", "utf-8", "cp1250"):
        try:
            with open(path, "rb") as fh:
                raw = fh.read()
            text = raw.decode(enc)
            used_crlf = b"\r\n" in raw
            # Normalize to LF for processing
            text = text.replace("\r\n", "\n").replace("\r", "\n")
            return text, used_crlf, enc
        except (UnicodeDecodeError, LookupError):
            continue
    print(f"ERROR: Cannot decode {path} with utf-8-sig / utf-8 / cp1250", file=sys.stderr)
    sys.exit(2)


def write_atomic(path, text, used_crlf, encoding, no_backup):
    """Write atomically via temp file; optionally keep a .bak first."""
    if used_crlf:
        text = text.replace("\n", "\r\n")

    encoded = text.encode(encoding if encoding != "utf-8-sig" else "utf-8")

    # Backup existing output
    if not no_backup and os.path.exists(path):
        bak = path + ".bak"
        try:
            import shutil
            shutil.copy2(path, bak)
            print(f"  Backup: {bak}")
        except OSError as exc:
            print(f"WARNING: Could not create backup: {exc}", file=sys.stderr)

    # Atomic write via temp file in same directory
    dir_ = os.path.dirname(os.path.abspath(path))
    fd, tmp = tempfile.mkstemp(dir=dir_, suffix=".tmp")
    try:
        with os.fdopen(fd, "wb") as fh:
            fh.write(encoded)
        os.replace(tmp, path)
    except OSError as exc:
        try:
            os.unlink(tmp)
        except OSError:
            pass
        print(f"ERROR writing {path}: {exc}", file=sys.stderr)
        sys.exit(2)


# ---------------------------------------------------------------------------
# Validation phases
# ---------------------------------------------------------------------------

def count_forall(text):
    """Count FORALL keyword occurrences that are actual statements (not comments)."""
    count = 0
    for line in text.splitlines():
        stripped = line.lstrip()
        if stripped.upper().startswith("FORALL "):
            count += 1
    return count


def phase1_validate(text):
    """Verify all patterns exist with expected counts. Returns True or exits."""
    ok = True
    for t in TRANSFORMS:
        found = text.count(t["old"])
        if found != t["expected_count"]:
            print(
                f"  FAIL [{t['id']}] {t['desc']}: "
                f"expected {t['expected_count']} occurrence(s), found {found}"
            )
            ok = False
        else:
            print(f"  OK   [{t['id']}] {t['desc']}: found {found}x")
    return ok


def phase3_validate(text):
    """Verify no FORALL statements remain. Returns True or prints error."""
    remaining = count_forall(text)
    if remaining != 0:
        print(f"  FAIL: {remaining} FORALL statement(s) remain in output!")
        return False
    print("  OK   No FORALL statements in output.")
    return True


# ---------------------------------------------------------------------------
# Transforms
# ---------------------------------------------------------------------------

def apply_transforms(text):
    """Apply all 6 transformations sequentially."""
    for t in TRANSFORMS:
        text = text.replace(t["old"], t["new"], 1)
    return text


# ---------------------------------------------------------------------------
# Diff display
# ---------------------------------------------------------------------------

def show_diff(original, converted, src_label, dst_label):
    diff = list(
        difflib.unified_diff(
            original.splitlines(keepends=True),
            converted.splitlines(keepends=True),
            fromfile=src_label,
            tofile=dst_label,
            n=3,
        )
    )
    if not diff:
        print("  (no differences)")
        return
    print(f"  {len(diff)} diff lines")
    print()
    for line in diff:
        sys.stdout.write(line)
    print()


# ---------------------------------------------------------------------------
# Main
# ---------------------------------------------------------------------------

def parse_args():
    p = argparse.ArgumentParser(description=__doc__)
    p.add_argument(
        "--input",
        default=os.path.join(
            os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
            "input",
            "PACK_CONTAFIN.pck",
        ),
        help="Source file (default: input/PACK_CONTAFIN.pck)",
    )
    p.add_argument(
        "--output",
        default=None,
        help="Output file (default: input/PACK_CONTAFIN_ORACLE_10G.pck)",
    )
    p.add_argument("--dry-run", action="store_true", help="Show diff only, do not write")
    p.add_argument("--no-backup", action="store_true", help="Skip .bak creation")
    return p.parse_args()


def main():
    args = parse_args()

    input_path = args.input
    output_path = args.output or os.path.join(
        os.path.dirname(input_path), "PACK_CONTAFIN_ORACLE_10G.pck"
    )

    print(f"Input:  {input_path}")
    print(f"Output: {output_path}")
    print()

    # Load
    try:
        original, used_crlf, encoding = load_file(input_path)
    except FileNotFoundError:
        print(f"ERROR: Input file not found: {input_path}", file=sys.stderr)
        sys.exit(2)

    forall_count = count_forall(original)
    print(f"Input FORALL statements: {forall_count}  (encoding={encoding}, crlf={used_crlf})")
    print()

    # Idempotency check
    if forall_count == 0:
        print("Already converted (0 FORALL statements). Nothing to do.")
        sys.exit(0)

    # Phase 1 — pre-validate
    print("Phase 1: Pre-validate patterns")
    if not phase1_validate(original):
        print()
        print("ERROR: One or more patterns not found. Aborting without changes.")
        sys.exit(1)
    print()

    # Apply transforms
    converted = apply_transforms(original)

    # Phase 3 — post-validate
    print("Phase 3: Post-validate output")
    if not phase3_validate(converted):
        print()
        print("ERROR: FORALL statements remain after conversion. Aborting.")
        sys.exit(1)
    print()

    # Show diff
    print("Diff:")
    show_diff(original, converted, input_path, output_path)

    if args.dry_run:
        print("Dry-run mode: no files written.")
        sys.exit(0)

    # Write
    write_atomic(output_path, converted, used_crlf, encoding, args.no_backup)
    print(f"Written: {output_path}")
    print("Done.")
    sys.exit(0)


if __name__ == "__main__":
    main()