"""The alteration engine: a knob vector -> a layered RenderPlan (design §4, §5).

Right axis (reframed session 0013): a DETERMINISTIC, real-time dream applied live
to the base footage — a STILL altered state, not the old pre-baked SD variant that
churned across the loop (Right-axis dream design,
docs/superpowers/specs/2026-06-22-right-axis-deterministic-dream-design.md). The
Left axis carries its knob LEVEL so a runtime annotation track can pick which
labels show, and a frozen `Calibration` parameterizes the knob->strength gains so
they can be tuned by eye in the simulator and baked into DEFAULT_CALIBRATION.

Layers compose per §4.2:
  - Substrate: ColorGrade (Dark/Light mood, center = identity §5) + the Right Dream
    (deterministic luminous haze, applied client-side from `dream.intensity`).
  - Overlay: AnalyticalOverlay (Left) + the affect channel, composited on top.
Left and Right stack (different layers); Dark/Light are the two poles of one
mood grade.
"""

from __future__ import annotations

from dataclasses import dataclass

from hef.selection import Coordinate

KNOB_MAX = 4  # knob full-scale (0..4)


def _clamp(x: float, lo: float, hi: float) -> float:
    return max(lo, min(hi, x))


@dataclass(frozen=True)
class Calibration:
    """Tunable knob->strength curves (settled by eye in the sim, then baked).

    - mood_gain: scales the signed Dark/Light tone (result clamped to [-1, 1]).
    - overlay_gain: scales the Left overlay (and affect) intensity (clamped [0, 1]).
    - dream_gain: scales the Right deterministic-dream intensity (clamped [0, 1]).
    """

    mood_gain: float = 1.0
    overlay_gain: float = 1.0
    dream_gain: float = 1.0


# The LOCKED calibration (session 0010, 2026-06-07) — settled by eye in the
# simulator, closing the open session-0006 knob->strength decision. Convention:
# every experience knob runs 0 = off .. 4 = max, and equal Dark/Light = identity
# (raw footage); there is no "centered at 2 = no push" coordinate.
#   - mood_gain = 1.0: full Dark/Light knob reaches the full mood grade. By-eye
#     evidence (POC renders + sim, after the dark-grade fix this session) shows
#     full tilt is peaceful on every axis, so no softening is warranted.
#   - overlay_gain = 1.0: full Left = opacity 1.0; the HUD is legible, not
#     overwhelming, sitting above the grade.
#   - dream_gain = 1.0: full Right = dream intensity 1.0; the deterministic
#     luminous haze (Right-axis dream design, session 0013) reaches full strength.
# These are unity by deliberate choice, not as placeholders. The gains stay
# parameterized so a different feel is one edit away; test_default_calibration_is_locked
# guards the values from drifting silently.
DEFAULT_CALIBRATION = Calibration(
    mood_gain=1.0,
    overlay_gain=1.0,
    dream_gain=1.0,
)


@dataclass(frozen=True)
class ColorGrade:
    """Mood-axis grade (§5). `tone` is signed: >0 warm yellow->white (light),
    <0 cool blue->black (dark), 0 = identity (raw, ungraded)."""

    tone: float

    @property
    def is_identity(self) -> bool:
        return self.tone == 0.0


@dataclass(frozen=True)
class AnalyticalOverlay:
    """Left axis (§4.1): analytical HUD/annotation, composited on top at runtime.
    `level` is the Left knob (0..4); a runtime annotation track uses it to pick
    which labels appear. `intensity` 0..1 is the overlay opacity/strength."""

    level: int
    intensity: float


@dataclass(frozen=True)
class AffectOverlay:
    """Affect channel (Left x Right): emotion-words surfaced only when BOTH the
    analytical (Left) and dreamlike (Right) knobs are up. `strength` is
    `min(left, right)` (0..4) — a runtime affect track picks which feeling words
    appear by it; `intensity` 0..1 is their opacity. The dream leaking into the
    machine's reading (affect-channel design, session 0013)."""

    strength: int
    intensity: float


@dataclass(frozen=True)
class Dream:
    """Right axis: a deterministic, real-time dream applied live to the base
    footage — a STILL altered state (Right-axis dream design, session 0013),
    NOT the old pre-baked SD variant that churned across the loop. `strength` is
    the Right knob (0..4); `intensity` 0..1 is the dream's strength (the client
    maps it to the luminous-haze look, the way it maps `grade.tone` to a filter)."""

    strength: int
    intensity: float


@dataclass(frozen=True)
class RenderPlan:
    """The full layered alteration for one knob vector (§4.2)."""

    grade: ColorGrade
    overlay: AnalyticalOverlay
    affect: AffectOverlay
    dream: Dream

    @property
    def is_identity(self) -> bool:
        """True when the plan leaves the neutral base un-altered. Affect needs no
        clause: `min(left,right) > 0` implies `left > 0`, so `overlay.level > 0`
        already makes a plan with active affect non-identity."""
        return (
            self.grade.is_identity
            and self.overlay.level == 0
            and self.dream.strength == 0
        )


def _overlay_intensity(left: int, cal: Calibration) -> float:
    return _clamp(cal.overlay_gain * left / KNOB_MAX, 0.0, 1.0)


def _affect_strength(left: int, right: int) -> int:
    """Affect surfaces only when BOTH knobs are up — gated by the smaller one."""
    return min(left, right)


def _affect_intensity(left: int, right: int, cal: Calibration) -> float:
    return _clamp(cal.overlay_gain * _affect_strength(left, right) / KNOB_MAX, 0.0, 1.0)


def _dream_intensity(right: int, cal: Calibration) -> float:
    return _clamp(cal.dream_gain * right / KNOB_MAX, 0.0, 1.0)


def _mood_tone(dark: int, light: int, cal: Calibration) -> float:
    return _clamp(cal.mood_gain * (light - dark) / KNOB_MAX, -1.0, 1.0)


def plan_alteration(
    coord: Coordinate, calibration: Calibration = DEFAULT_CALIBRATION
) -> RenderPlan:
    """Map a knob vector to its layered RenderPlan (design §4)."""
    return RenderPlan(
        grade=ColorGrade(tone=_mood_tone(coord.dark, coord.light, calibration)),
        overlay=AnalyticalOverlay(
            level=coord.left,
            intensity=_overlay_intensity(coord.left, calibration),
        ),
        affect=AffectOverlay(
            strength=_affect_strength(coord.left, coord.right),
            intensity=_affect_intensity(coord.left, coord.right, calibration),
        ),
        dream=Dream(
            strength=coord.right,
            intensity=_dream_intensity(coord.right, calibration),
        ),
    )


def render_plan_to_dict(plan: RenderPlan) -> dict:
    """JSON-serializable form for the simulator API."""
    return {
        "grade": {"tone": plan.grade.tone},
        "overlay": {"level": plan.overlay.level, "intensity": plan.overlay.intensity},
        "affect": {"strength": plan.affect.strength, "intensity": plan.affect.intensity},
        "dream": {"strength": plan.dream.strength, "intensity": plan.dream.intensity},
        "is_identity": plan.is_identity,
    }