"""Music mode's queue: what plays next, shuffle and repeat. Shuffling
reorders the queue itself (the current track first), so the Queue page
always shows the real play order; turning it off brings the original order
back. Saved between runs as Session.toml."""

import random
from dataclasses import dataclass, field
from typing import Optional

import tomlkit

from Core import ConfigDir, SessionPath

RepeatModes = ["Off", "All", "One"]
RestartAfterMs = 3000  # Previous restarts the track when it's further in than this


@dataclass
class PlayQueue:
    Paths: list[str] = field(default_factory=list)
    Index: int = -1  # into Paths; -1 = nothing
    Shuffle: bool = False
    Repeat: str = "Off"
    Unshuffled: list[str] = field(default_factory=list)  # the order before shuffling

    @property
    def Current(self) -> Optional[str]:
        return self.Paths[self.Index] if 0 <= self.Index < len(self.Paths) else None

    def Set(self, Paths: list[str], Start: int = 0) -> None:
        """Replaces the queue, e.g. with an album, starting at Paths[Start]."""
        self.Paths = list(Paths)
        self.Index = Start if Paths else -1
        self.Unshuffled = list(Paths)
        if self.Shuffle and Paths:
            self._ShuffleRest()

    def _ShuffleRest(self) -> None:
        Current = self.Paths[self.Index]
        Rest = self.Paths[: self.Index] + self.Paths[self.Index + 1 :]
        random.shuffle(Rest)
        self.Paths = [Current] + Rest
        self.Index = 0

    def SetShuffle(self, Enabled: bool) -> None:
        if Enabled == self.Shuffle:
            return
        self.Shuffle = Enabled
        if not self.Paths:
            return
        if Enabled:
            self.Unshuffled = list(self.Paths)
            self._ShuffleRest()
        else:
            Current = self.Current
            self.Paths = self.Unshuffled or self.Paths
            self.Index = self.Paths.index(Current) if Current in self.Paths else 0

    def Next(self, Finished: bool = False) -> Optional[int]:
        """The index to play after the current one (None: stop). Finished means
        the track ran out by itself, which is when Repeat One applies."""
        if not self.Paths:
            return None
        if Finished and self.Repeat == "One":
            return self.Index
        if self.Index + 1 < len(self.Paths):
            return self.Index + 1
        return 0 if self.Repeat != "Off" or not Finished else None

    def Previous(self) -> Optional[int]:
        if not self.Paths:
            return None
        if self.Index > 0:
            return self.Index - 1
        return len(self.Paths) - 1 if self.Repeat == "All" else 0

    # --- Editing ------------------------------------------------------------

    def PlayNext(self, Paths: list[str]) -> None:
        At = self.Index + 1 if self.Index >= 0 else 0
        self.Paths[At:At] = Paths
        self.Unshuffled.extend(Paths)
        if self.Index < 0:
            self.Index = 0

    def Append(self, Paths: list[str]) -> None:
        self.Paths.extend(Paths)
        self.Unshuffled.extend(Paths)
        if self.Index < 0 and self.Paths:
            self.Index = 0

    def Remove(self, At: int) -> None:
        Removed = self.Paths.pop(At)
        if Removed in self.Unshuffled:
            self.Unshuffled.remove(Removed)
        if At < self.Index or (At == self.Index and self.Index >= len(self.Paths)):
            self.Index -= 1
        if not self.Paths:
            self.Index = -1

    def Move(self, Old: int, New: int) -> None:
        Item = self.Paths.pop(Old)
        self.Paths.insert(New, Item)
        if Old == self.Index:
            self.Index = New
        elif Old < self.Index <= New:
            self.Index -= 1
        elif New <= self.Index < Old:
            self.Index += 1

    def Clear(self) -> None:
        self.Paths, self.Unshuffled, self.Index = [], [], -1


@dataclass
class Session:
    Queue: PlayQueue = field(default_factory=PlayQueue)
    Position: int = 0  # milliseconds into the current track
    View: str = "Songs"

    def Save(self) -> None:
        Document = tomlkit.document()
        Document["View"] = self.View
        Document["Position"] = int(self.Position)
        Document["Index"] = self.Queue.Index
        Document["Shuffle"] = self.Queue.Shuffle
        Document["Repeat"] = self.Queue.Repeat
        for Key, Paths in (("Paths", self.Queue.Paths), ("Unshuffled", self.Queue.Unshuffled)):
            Document[Key] = tomlkit.array()
            Document[Key].multiline(True)
            Document[Key].extend(Paths)
        ConfigDir.mkdir(parents=True, exist_ok=True)
        SessionPath.write_text(tomlkit.dumps(Document), encoding="utf-8")


def LoadSession() -> Session:
    try:
        Data = tomlkit.parse(SessionPath.read_text(encoding="utf-8")).unwrap()
    except (OSError, tomlkit.exceptions.TOMLKitError):
        return Session()
    Paths = [str(Item) for Item in Data.get("Paths", []) if isinstance(Item, str)]
    Index = Data.get("Index", -1)
    Queue = PlayQueue(
        Paths=Paths,
        Index=Index if isinstance(Index, int) and 0 <= Index < len(Paths) else (0 if Paths else -1),
        Shuffle=bool(Data.get("Shuffle", False)),
        Repeat=Data.get("Repeat") if Data.get("Repeat") in RepeatModes else "Off",
        Unshuffled=[str(Item) for Item in Data.get("Unshuffled", []) if isinstance(Item, str)],
    )
    return Session(Queue=Queue, Position=int(Data.get("Position", 0) or 0), View=str(Data.get("View", "Songs")))