"""The drawing decision table. Pure: no database, no M-Files.

`decide(target, found, same_file=...)` says what the drawing job does to one packet for one lookup. Note texts are
the app's own (from the old revMismatch and draftLine in visual.js, "-" in place of the em-dash), never M-Files'
note passed through, except inside the lookup_failed text.

Rows, in the order they are tried:
 1. lookup failed -> flag lookup_failed, keep what is attached (state lookup_failed only when it was needed).
 2. past draft, a pending feed change order waits for this drawing at the released rev -> stage_for_co.
    Past draft, the pending change order already stages this drawing at the released rev -> unchanged, or
    stage_for_co again when M-Files has a different file for that rev.
 3. no released rev, a draft rev or a drafting assignment -> flag not_released with the drafting status.
 4. no released rev otherwise -> flag not_found.
 5. VISUAL rev not a number (and no approved rev equal to M-Files') -> flag bad_rev, not attached.
 6. revs differ (and no approved rev equal to M-Files') -> flag rev_mismatch. The job stages the M-Files copy
    for Clerical Supervisor approval on drafts only.
 7. revs match, draft with a hand drawing -> unchanged (the feed already took the hand drawing off on a rev move).
 8. revs match, draft with this very file attached at this rev -> unchanged.
 9. revs match, draft -> attach ("sheet of drawing <base>" for an H sheet).
10. revs match, past draft, nothing attached -> unchanged.
11. revs match, past draft, same file as attached -> unchanged.
12. revs match, past draft, a pending change order already stages this file, or Clerical rejected a change order
    for this file -> unchanged.
13. revs match, past draft, attached rev lower -> open_co "M-Files released rev N of <dwg>; this packet has rev M".
14. revs match, past draft, attached rev equal, new file -> open_co "M-Files re-released rev N of <dwg> (new file)".
15. revs match, past draft, attached rev higher or not a number -> unchanged.
"""

from __future__ import annotations

from dataclasses import dataclass

from .lookup import Found

LOOKUP_FAILED = "lookup_failed"
NOT_RELEASED = "not_released"
NOT_FOUND = "not_found"
BAD_REV = "bad_rev"
REV_MISMATCH = "rev_mismatch"
ATTACH = "attach"
UNCHANGED = "unchanged"
OPEN_CO = "open_co"
STAGE_FOR_CO = "stage_for_co"

KINDS = (ATTACH, UNCHANGED, REV_MISMATCH, NOT_RELEASED, NOT_FOUND, LOOKUP_FAILED, BAD_REV, OPEN_CO, STAGE_FOR_CO)
FLAG_KINDS = (LOOKUP_FAILED, NOT_RELEASED, NOT_FOUND, BAD_REV, REV_MISMATCH)

# drawing_state enum values (0003). bad_rev has no state of its own: it is a rev mismatch Clerical can approve.
STATE_OF = {NOT_RELEASED: "not_released", NOT_FOUND: "not_found", BAD_REV: "rev_mismatch", REV_MISMATCH: "rev_mismatch"}
HELD_STATES = ("attached", "hand")

NOT_FOUND_NOTE = "Drawing not in M-Files - check the drawing number in VISUAL"
_FAILED_PREFIX = "M-Files lookup failed: "


@dataclass(frozen=True)
class Target:
    dwg: str
    visual_rev: str
    attached_rev: str | None  # rev of the live drawing pages; None when no drawing page is attached
    attached_sha: bytes | None
    status: str  # packet status
    drawing_state: str
    has_hand_drawing: bool
    rev_ok: str | None  # the rev Clerical approved for this VISUAL rev, if any
    # Additions to the contract, all defaulted: the pending feed change order (origin visual or drawing), if any.
    co_waiting: tuple[str, str] | None = None  # (dwg, rev) the pending CO waits for
    co_staged: tuple[str, str] | None = None  # (dwg, rev) the pending CO already stages
    co_pending: bool = False
    co_staged_sha: bytes | None = None  # sha256 of the file the pending CO already stages
    rejected_sha: bytes | None = None  # sha256 staged on the last drawing-origin CO Clerical rejected


@dataclass(frozen=True)
class Decision:
    kind: str
    flag: str | None
    drawing_state: str
    note: str


def _int(v: object) -> int | None:
    s = "" if v is None else str(v).strip()
    return int(s) if s.isdigit() else None


def draft_line(f: Found) -> str:
    """The old draftLine: "rev N <where>", or "in drafting, no released PDF yet", or ""."""
    if f.draft_rev is not None and f.draft_where:
        return f"rev {f.draft_rev} {f.draft_where}"
    if f.in_drafting:
        return "in drafting, no released PDF yet"
    if f.draft_rev is not None:
        return f"rev {f.draft_rev}"
    return ""


def failed_note(f: Found) -> str:
    detail = (f.note or "").strip()
    if detail.startswith(_FAILED_PREFIX):  # MFilesKit's own note already carries the prefix
        detail = detail[len(_FAILED_PREFIX) :]
    return f"{_FAILED_PREFIX}{detail or 'no detail'}"


def rev_confirmed(t: Target, f: Found) -> bool:
    """The old revConfirmed: M-Files' released rev is the rev VISUAL calls, or Clerical approved that rev."""
    if not f.ok or f.rev is None:
        return False
    v = _int(t.visual_rev)
    if v is not None and v == f.rev:
        return True
    return t.rev_ok is not None and str(t.rev_ok).strip() == str(f.rev)


def decide(t: Target, f: Found, *, same_file: bool, fetched_sha: bytes | None = None) -> Decision:
    """What to do to one packet.

    `same_file`: the M-Files file has the sha256 of the attached drawing asset. `fetched_sha`: the sha256 of the
    M-Files file, when it was fetched (row 12 compares it with the pending and the rejected change orders).
    """
    held = t.drawing_state in HELD_STATES
    draft = t.status == "draft"

    def flag(kind: str, note: str) -> Decision:
        return Decision(kind, kind, t.drawing_state if held else STATE_OF[kind], note)

    def keep(kind: str, note: str = "") -> Decision:
        return Decision(kind, None, t.drawing_state, note)

    # 1
    if not f.ok:
        return Decision(
            LOOKUP_FAILED,
            LOOKUP_FAILED,
            LOOKUP_FAILED if t.drawing_state == "needed" else t.drawing_state,
            failed_note(f),
        )
    # 2
    if not draft and f.rev is not None and t.co_waiting is not None:
        w_dwg, w_rev = t.co_waiting
        if w_dwg.strip() == t.dwg.strip() and str(w_rev).strip() == str(f.rev):
            return keep(STAGE_FOR_CO, f"Drawing for the change order is in M-Files (rev {f.rev})")
    if not draft and f.rev is not None and t.co_staged is not None:
        s_dwg, s_rev = t.co_staged
        if s_dwg.strip() == t.dwg.strip() and str(s_rev).strip() == str(f.rev):
            if fetched_sha is not None and t.co_staged_sha is not None and fetched_sha != t.co_staged_sha:
                return keep(STAGE_FOR_CO, f"New file for rev {f.rev} in M-Files; staged again for the change order")
            return keep(UNCHANGED, f"Rev {f.rev} is staged on the pending change order")
    # 3, 4
    if f.rev is None:
        d = draft_line(f)
        if d:
            on = f" (sheet of {f.base})" if f.base else ""
            return flag(NOT_RELEASED, f"Not released in M-Files yet{on} - drafting status: {d}")
        return flag(NOT_FOUND, NOT_FOUND_NOTE)
    approved = t.rev_ok is not None and str(t.rev_ok).strip() == str(f.rev)
    vrev = (t.visual_rev or "").strip()
    v = _int(vrev)
    if not approved:
        # 5
        if v is None:
            return flag(BAD_REV, f"VISUAL rev {vrev or '-'} is not a number; M-Files has rev {f.rev} - not attached")
        # 6
        if v != f.rev:
            d = f"; drafting status: {draft_line(f)}" if f.draft_rev is not None and f.draft_rev > f.rev else ""
            return flag(REV_MISMATCH, f"Rev mismatch: VISUAL calls rev {vrev}, M-Files has rev {f.rev}{d}")
    sheet = f"sheet of drawing {f.base}" if f.base else ""
    if draft:
        # 7
        if t.has_hand_drawing:
            return keep(UNCHANGED, "A drawing uploaded by hand stays at the same rev")
        # 8
        if t.drawing_state == "attached" and same_file and t.attached_rev == str(f.rev):
            return keep(UNCHANGED, sheet)
        # 9
        return Decision(ATTACH, None, "attached", sheet)
    # 10, 11
    if t.attached_rev is None or same_file:
        return keep(UNCHANGED, sheet)
    # 12
    if fetched_sha is not None and fetched_sha in (t.co_staged_sha, t.rejected_sha):
        return keep(UNCHANGED, sheet)
    att = _int(t.attached_rev)
    if att is None or att > f.rev:
        return keep(UNCHANGED, sheet)  # 15
    if att < f.rev:
        reason = f"M-Files released rev {f.rev} of {t.dwg}; this packet has rev {att}"
    else:
        reason = f"M-Files re-released rev {f.rev} of {t.dwg} (new file)"
    return keep(OPEN_CO, reason)