"""Phase 3 — the level ladder (plan-phase3-results-ux.md §4.1, R1).

A single integer **level** summarising how far up the quality ladder a recipe run climbed, with
YunoHost semantics: **a gap caps the level** — you only earn level L if every rung 1..L was a clean
PASS. The first rung that is not a clean PASS (a real FAIL *or* genuinely N/A for this recipe) stops
the climb; `cap_reason` records why. This is deliberately conservative: presentation must NEVER make
a run look greener than its tests (plan §6 cardinal guardrail), so an N/A rung caps just like a fail
(the L5 example in §4.1 — "recipes with no integration surface cap at L4 by definition" — is exactly
this: N/A caps, with a recorded reason so the level is *fair*, not inflated).

The ladder (§4.1):
  L0 — install failed / app never became healthy.
  L1 — Installs: deploys + passes health/readiness.
  L2 — Upgrades: previous published version → PR version, stays healthy, data intact.
  L3 — Backup/restore: seeded data survives backup → wipe → restore.
  L4 — Functional: recipe-specific functional tests pass.
  L5 — Integration: SSO/OIDC + cross-app integration tests pass.
  L6 — Recipe-local: the recipe repo's own tests/ (D4) pass and are merged.

This module is PURE (no I/O) so it is cheaply unit-testable and the Adversary can re-run the unit
test cold (`cc-ci-run -m pytest tests/unit/test_level.py -q`). The orchestrator
(`run_recipe_ci.py`) is responsible for translating its raw per-tier results + deps/SSO signals into
the rung-status dict this function consumes; that mapping is documented in DECISIONS.md (Phase 3).

Rung status vocabulary (each rung ∈ these three):
  "pass" — the rung was exercised and passed.
  "fail" — the rung was exercised and failed.
  "na"   — the rung does not apply to this recipe (e.g. only one published version → no upgrade;
           not backup-capable; no SSO/integration surface; no recipe-local tests). N/A is NOT a
           failure, but it DOES cap the climb (with a distinct cap_reason) so the level never
           overstates what was actually verified.
"""

from __future__ import annotations

# The climbable rungs in ascending order. install (L1) is the foundation; L0 means install itself
# did not pass. Each later rung requires every earlier rung to be a clean PASS.
RUNGS = ("install", "upgrade", "backup_restore", "functional", "integration", "recipe_local")

# Human-readable label per rung level, for cap_reason + the summary card.
RUNG_LABEL = {
    1: "install (deploy + health)",
    2: "upgrade (prev published → PR)",
    3: "backup/restore (data integrity)",
    4: "functional (recipe-specific tests)",
    5: "integration (SSO/OIDC + cross-app)",
    6: "recipe-local (recipe repo tests/)",
}

VALID = {"pass", "fail", "na"}


def compute_level(rungs: dict[str, str]) -> tuple[int, str]:
    """Map a rung-status dict → (level 0..6, cap_reason).

    `rungs` must contain a status in {"pass","fail","na"} for every name in RUNGS. The level is the
    highest L such that rungs[1..L] are all "pass"; the first non-"pass" rung caps the climb. L0 is
    returned when the install rung itself is not "pass" (install failed / never healthy).

    cap_reason explains where the climb stopped:
      - "" (empty) when the recipe earned the top rung (L6, full clean climb).
      - "L<k> <label> FAILED" when a rung was exercised and failed.
      - "L<k> <label> N/A" when a rung does not apply to this recipe.
    Returns the reason for the FIRST rung that stopped the climb (the binding constraint).
    """
    for name in RUNGS:
        st = rungs.get(name)
        if st not in VALID:
            raise ValueError(
                f"rung {name!r} has invalid status {st!r} (expect one of {sorted(VALID)})"
            )

    # L0: install did not pass.
    if rungs["install"] != "pass":
        if rungs["install"] == "fail":
            return 0, "L1 " + RUNG_LABEL[1] + " FAILED"
        # install N/A is not a real-world state for a deploy run, but handle it for totality.
        return 0, "L1 " + RUNG_LABEL[1] + " N/A"

    # Climb: stop at the first rung that is not a clean pass.
    level = 0
    for idx, name in enumerate(RUNGS, start=1):
        if rungs[name] == "pass":
            level = idx
            continue
        # first non-pass rung — caps the climb
        kind = "FAILED" if rungs[name] == "fail" else "N/A"
        return level, f"L{idx} {RUNG_LABEL[idx]} {kind}"

    # Full clean climb to the top rung.
    return level, ""


def backup_restore_status(backup: str | None, restore: str | None, backup_capable: bool) -> str:
    """Collapse the backup + restore tier results into the single L3 rung status.

    Both tiers must pass for the rung to pass (the rung is "seeded data survives backup→wipe→restore",
    which is only verified if BOTH the backup and the restore tier are green). If the recipe is not
    backup-capable, both tiers skip → the rung is N/A (caps at L2, recorded). A fail in either tier
    fails the rung.
    """
    if not backup_capable:
        return "na"
    vals = {backup, restore}
    if "fail" in vals:
        return "fail"
    if backup == "pass" and restore == "pass":
        return "pass"
    # any skip/None while backup-capable → not verified → treat as N/A (cannot claim L3)
    return "na"


def tier_to_rung(status: str | None) -> str:
    """Map a single tier result ('pass'|'fail'|'skip'|None) to a rung status. 'skip'/None → 'na'
    (the tier did not apply / did not run), so it caps the climb without being counted as a failure."""
    if status == "pass":
        return "pass"
    if status == "fail":
        return "fail"
    return "na"