"""Caster-level healing scaling (Package S5b).

PF1e (SRD spells/cure-light-wounds.md): "cures 1d8 points of damage + 1 point
per caster level (maximum +5)"; (spells/cure-moderate-wounds.md): "cures 2d8
points of damage + 1 point per caster level (maximum +10)". A HealEffect may
declare ``"scaling_flat": {"amount": 1, "per_levels": 1, "max": 5}`` reusing
the S1b ``DamageFlatScaling`` machinery; the cast resolves it against the
caster's level.

Unit tests pin ``HealEffect.effective_formula`` arithmetic and the loader;
integration casts pin that the scaled formula — and ONLY the scaled formula —
drives the dice consumed and Maximize Spell.
"""

from __future__ import annotations

from pathlib import Path
from typing import TYPE_CHECKING

import pytest

from pf1e_simulator.combat import CombatantState, CombatEngine
from pf1e_simulator.dice import parse_dice
from pf1e_simulator.grid import Grid
from pf1e_simulator.map import MapSpec, TerrainType
from pf1e_simulator.rng import ScriptedRng
from pf1e_simulator.spells import (
    DamageFlatScaling,
    HealEffect,
    SpellSpec,
    load_spell,
)
from tests.test_observation_enriched import make_combatant, make_state

if TYPE_CHECKING:
    from pf1e_simulator.models import Combatant

_SPELLS_DIR = Path(__file__).resolve().parent.parent / "data" / "spells"


# ---------------------------------------------------------------------------
# unit: effective_formula arithmetic
# ---------------------------------------------------------------------------


def test_flat_scaling_grows_with_level_and_stops_at_cap() -> None:
    """Given: 1d8 + 1 per caster level, maximum +5 (SRD Cure Light Wounds)
    When: effective_formula resolves for levels 0/1/4/7
    Then: 1d8, 1d8+1, 1d8+4, 1d8+5 — the cap binds, the base dice untouched."""
    effect = HealEffect(
        formula=parse_dice("1d8"),
        scaling_flat=DamageFlatScaling(amount=1, per_levels=1, max_amount=5),
    )
    assert effect.effective_formula(0) == parse_dice("1d8")
    assert effect.effective_formula(1) == parse_dice("1d8+1")
    assert effect.effective_formula(4) == parse_dice("1d8+4")
    assert effect.effective_formula(7) == parse_dice("1d8+5")


def test_no_scaling_is_behaviour_change_free() -> None:
    """Given: a HealEffect without a scaling_flat spec
    When: effective_formula resolves at any level
    Then: the base formula is returned unchanged."""
    effect = HealEffect(formula=parse_dice("1d8+2"))
    assert effect.effective_formula(0) == parse_dice("1d8+2")
    assert effect.effective_formula(20) == parse_dice("1d8+2")


def test_loader_parses_heal_scaling_flat(tmp_path: Path) -> None:
    """Given: heal effects with and without a "scaling_flat" spec
    When: load_spell parses them
    Then: the spec lands on the HealEffect; the plain heal keeps None."""
    spell_file = tmp_path / "scaled_heal.json"
    spell_file.write_text(
        '{"name": "Scaled Heal", "level": 1, "school": "conjuration",'
        ' "range": "touch", "save": "will", "effects": ['
        ' {"type": "heal", "formula": "1d8",'
        '  "scaling_flat": {"amount": 1, "per_levels": 1, "max": 5}},'
        ' {"type": "heal", "formula": "1"}]}'
    )
    spell = load_spell(spell_file)
    scaled, plain = spell.effects
    assert isinstance(scaled, HealEffect)
    assert isinstance(plain, HealEffect)
    assert scaled.scaling_flat == DamageFlatScaling(
        amount=1, per_levels=1, max_amount=5
    )
    assert plain.scaling_flat is None


def test_loader_rejects_bad_heal_scaling_flat(tmp_path: Path) -> None:
    """Given: a heal scaling_flat with per_levels < 1
    When: load_spell parses it
    Then: it is a data error (the shared S1b validator refuses)."""
    spell_file = tmp_path / "bad_heal.json"
    spell_file.write_text(
        '{"name": "Bad Heal", "level": 1, "school": "conjuration",'
        ' "range": "touch", "save": "will", "effects": ['
        ' {"type": "heal", "formula": "1d8",'
        '  "scaling_flat": {"amount": 1, "per_levels": 0, "max": 5}}]}'
    )
    with pytest.raises(ValueError, match="per_levels must be >= 1"):
        load_spell(spell_file)


# ---------------------------------------------------------------------------
# data: the SRD values are pinned on the shipped spell files
# ---------------------------------------------------------------------------


@pytest.mark.parametrize(
    ("filename", "base", "cap"),
    [("cure_light_wounds.json", "1d8", 5), ("cure_moderate_wounds.json", "2d8", 10)],
)
def test_cure_spells_carry_srd_scaling(filename: str, base: str, cap: int) -> None:
    """Given: the shipped cure spell JSON files
    When: they are loaded
    Then: the base dice carry no baked-in flat bonus and scaling_flat is
    +1 per level capped at the SRD maximum (spells/cure-light-wounds.md,
    spells/cure-moderate-wounds.md)."""
    spell = load_spell(_SPELLS_DIR / filename)
    (effect,) = spell.effects
    assert isinstance(effect, HealEffect)
    assert effect.formula == parse_dice(base)
    assert effect.scaling_flat is not None
    assert effect.scaling_flat.amount == 1
    assert effect.scaling_flat.per_levels == 1
    assert effect.scaling_flat.max_amount == cap


# ---------------------------------------------------------------------------
# integration: the scaled formula drives the cast
# ---------------------------------------------------------------------------


def _heal_spell(name: str, formula: str, cap: int, level: int) -> SpellSpec:
    return SpellSpec(
        name=name,
        level=level,
        school="conjuration",
        range="touch",
        save="will",
        effects=(
            HealEffect(
                formula=parse_dice(formula),
                scaling_flat=DamageFlatScaling(
                    amount=1, per_levels=1, max_amount=cap
                ),
            ),
        ),
    )


_CLW = _heal_spell("Cure Light Wounds", "1d8", 5, 1)
_CMW = _heal_spell("Cure Moderate Wounds", "2d8", 10, 2)


def _cast_heal(
    caster: Combatant,
    target: Combatant,
    spell: SpellSpec,
    start_hp: int,
    rolls: list[int],
    *,
    metamagic: tuple[str, ...] = (),
) -> tuple[CombatEngine, CombatantState]:
    """Cast a touch heal on a same-side ally (no delivery attack needed).

    The queue is [Will save, heal dice]: the save is rolled (harmless spells
    keep their save line) and a scripted 1 always fails it, which for a
    harmless effect means the healing is NOT negated.
    """
    legend = {".": TerrainType(type="floor", move_cost=1)}
    grid = Grid.from_spec(
        MapSpec(name="open", terrain=tuple(["." * 8] * 8), legend=legend)
    )
    c = make_state(caster, "players", (0, 0))
    t = make_state(target, "players", (1, 0))
    t.hp = start_hp
    engine = CombatEngine(
        ScriptedRng(rolls), grid, [c, t], spell_registry={spell.name: spell}
    )
    engine._cast_spell(c, t, spell.name, metamagic=metamagic)
    return engine, t


def _caster(level: int, spell: SpellSpec, *, slots: dict[int, int]) -> Combatant:
    caster = make_combatant("healer", spells=[spell.name], spell_slots=slots)
    return caster.model_copy(update={"level": level})


def test_cast_heals_with_flat_bonus_at_low_level() -> None:
    """Given: a level-4 caster curing 1d8 + 1/level (max +5), ally at 10/30
    When: the scripted d8 rolls 3
    Then: the ally gains 3 + 4 = 7 hp — the level bonus, not the cap."""
    caster = _caster(4, _CLW, slots={1: 1})
    target = make_combatant("foe", hp=30)
    _, t = _cast_heal(caster, target, _CLW, 10, [1, 3])
    assert t.hp == 17


def test_cast_heal_scales_and_caps_at_max() -> None:
    """Given: a level-12 caster (scaling would give +12, cap +5), ally at 28/30
    When: the scripted d8 rolls 8 (→ 8+5 = 13 healed)
    Then: the ally reaches hp_max — healing never overheals."""
    caster = _caster(12, _CLW, slots={1: 1})
    target = make_combatant("foe", hp=30)
    _, t = _cast_heal(caster, target, _CLW, 28, [1, 8])
    assert t.hp == 30


def test_moderate_cure_scales_to_its_own_cap() -> None:
    """Given: a level-8 caster of 2d8 + 1/level (max +10), ally at 50/100
    When: the scripted 2d8 roll 4+4 = 8
    Then: the heal is 8 + 8 = 16 — the level bonus, not the light cap."""
    caster = _caster(8, _CMW, slots={2: 1})
    target = make_combatant("foe", hp=100)
    _, t = _cast_heal(caster, target, _CMW, 50, [1, 4, 4])
    assert t.hp == 66


def test_maximize_metamagic_maximizes_the_scaled_heal() -> None:
    """Given: a level-3 caster who knows Maximize Spell curing 1d8 + 1/level
    When: the cast is maximized (slot 1 + adjustment 3 = slot 4)
    Then: the SCALED maximum (8 + 3 = 11) is healed — the scripted die is
    consumed but its value is overwritten (engine convention)."""
    caster = _caster(3, _CLW, slots={4: 1}).model_copy(
        update={"metamagic_feats": ["Maximize Spell"]}
    )
    target = make_combatant("foe", hp=30)
    _, t = _cast_heal(caster, target, _CLW, 10, [1, 1], metamagic=("Maximize Spell",))
    assert t.hp == 21