"""
Figment effect plugin — periodic SVG glyph overlay.

Owns the figment lifecycle: timer, SVG selection, state machine.
Delegates rendering to render_figment_overlay() in engine/layers.py.

Named FigmentEffect (not FigmentPlugin) to match the *Effect discovery
convention in effects_plugins/__init__.py.

NOT added to the EffectChain order — process() is a no-op. The overlay
rendering is handled by scroll.py calling get_figment_state().
"""

from __future__ import annotations

import random
from dataclasses import dataclass
from enum import Enum, auto
from pathlib import Path

from engine import config
from engine.effects.types import EffectConfig, EffectContext, EffectPlugin
from engine.figment_render import rasterize_svg
from engine.figment_trigger import FigmentAction, FigmentCommand, FigmentTrigger
from engine.themes import THEME_REGISTRY


class FigmentPhase(Enum):
    REVEAL = auto()
    HOLD = auto()
    DISSOLVE = auto()


@dataclass
class FigmentState:
    phase: FigmentPhase
    progress: float
    rows: list[str]
    gradient: list[int]
    center_row: int
    center_col: int


class FigmentEffect(EffectPlugin):
    name = "figment"
    config = EffectConfig(
        enabled=False,
        intensity=1.0,
        params={
            "interval_secs": 60,
            "display_secs": 4.5,
            "figment_dir": "figments",
        },
    )

    def __init__(
        self,
        figment_dir: str | None = None,
        triggers: list[FigmentTrigger] | None = None,
    ):
        self.config = EffectConfig(
            enabled=False,
            intensity=1.0,
            params={
                "interval_secs": 60,
                "display_secs": 4.5,
                "figment_dir": figment_dir or "figments",
            },
        )
        self._triggers = triggers or []
        self._phase: FigmentPhase | None = None
        self._progress: float = 0.0
        self._rows: list[str] = []
        self._gradient: list[int] = []
        self._center_row: int = 0
        self._center_col: int = 0
        self._timer: float = 0.0
        self._last_svg: str | None = None
        self._svg_files: list[str] = []
        self._scan_svgs()

    def _scan_svgs(self) -> None:
        figment_dir = Path(self.config.params["figment_dir"])
        if figment_dir.is_dir():
            self._svg_files = sorted(str(p) for p in figment_dir.glob("*.svg"))

    def process(self, buf: list[str], ctx: EffectContext) -> list[str]:
        return buf

    def configure(self, cfg: EffectConfig) -> None:
        # Preserve figment_dir if the new config doesn't supply one
        figment_dir = cfg.params.get(
            "figment_dir", self.config.params.get("figment_dir", "figments")
        )
        self.config = cfg
        if "figment_dir" not in self.config.params:
            self.config.params["figment_dir"] = figment_dir
        self._scan_svgs()

    def trigger(self, w: int, h: int) -> None:
        """Manually trigger a figment display."""
        if not self._svg_files:
            return

        # Pick a random SVG, avoid repeating
        candidates = [s for s in self._svg_files if s != self._last_svg]
        if not candidates:
            candidates = self._svg_files
        svg_path = random.choice(candidates)
        self._last_svg = svg_path

        # Rasterize
        try:
            self._rows = rasterize_svg(svg_path, w, h)
        except Exception:
            return

        # Pick random theme gradient
        theme_key = random.choice(list(THEME_REGISTRY.keys()))
        self._gradient = THEME_REGISTRY[theme_key].main_gradient

        # Center in viewport
        figment_h = len(self._rows)
        figment_w = max((len(r) for r in self._rows), default=0)
        self._center_row = max(0, (h - figment_h) // 2)
        self._center_col = max(0, (w - figment_w) // 2)

        # Start reveal phase
        self._phase = FigmentPhase.REVEAL
        self._progress = 0.0

    def get_figment_state(
        self, frame_number: int, w: int, h: int
    ) -> FigmentState | None:
        """Tick the state machine and return current state, or None if idle."""
        if not self.config.enabled:
            return None

        # Poll triggers
        for trig in self._triggers:
            cmd = trig.poll()
            if cmd is not None:
                self._handle_command(cmd, w, h)

        # Tick timer when idle
        if self._phase is None:
            self._timer += config.FRAME_DT
            interval = self.config.params.get("interval_secs", 60)
            if self._timer >= interval:
                self._timer = 0.0
                self.trigger(w, h)

        # Tick animation — snapshot current phase/progress, then advance
        if self._phase is not None:
            # Capture the state at the start of this frame
            current_phase = self._phase
            current_progress = self._progress

            # Advance for next frame
            display_secs = self.config.params.get("display_secs", 4.5)
            phase_duration = display_secs / 3.0
            self._progress += config.FRAME_DT / phase_duration

            if self._progress >= 1.0:
                self._progress = 0.0
                if self._phase == FigmentPhase.REVEAL:
                    self._phase = FigmentPhase.HOLD
                elif self._phase == FigmentPhase.HOLD:
                    self._phase = FigmentPhase.DISSOLVE
                elif self._phase == FigmentPhase.DISSOLVE:
                    self._phase = None

            return FigmentState(
                phase=current_phase,
                progress=current_progress,
                rows=self._rows,
                gradient=self._gradient,
                center_row=self._center_row,
                center_col=self._center_col,
            )

        return None

    def _handle_command(self, cmd: FigmentCommand, w: int, h: int) -> None:
        if cmd.action == FigmentAction.TRIGGER:
            self.trigger(w, h)
        elif cmd.action == FigmentAction.SET_INTENSITY and isinstance(
            cmd.value, (int, float)
        ):
            self.config.intensity = float(cmd.value)
        elif cmd.action == FigmentAction.SET_INTERVAL and isinstance(
            cmd.value, (int, float)
        ):
            self.config.params["interval_secs"] = float(cmd.value)
        elif cmd.action == FigmentAction.SET_COLOR and isinstance(cmd.value, str):
            if cmd.value in THEME_REGISTRY:
                self._gradient = THEME_REGISTRY[cmd.value].main_gradient
        elif cmd.action == FigmentAction.STOP:
            self._phase = None
            self._progress = 0.0