//! Actions: what views, keys and the command line ask for. Views never
//! change the document, the cursor or the mode themselves. They answer with
//! actions, and the app carries them out: [`Buffer::apply`] for a document
//! and its cursor, the app for the rest.
//!
//! [`Buffer::apply`]: super::buffer::Buffer::apply

use super::documents::BufferId;
use super::jumps::Place;
use super::mode::Connect;
use super::panes::Arrange;
use super::popup::{MenuFor, PickKind};
use super::repeat::Look;
use super::text_edit::StartEdit;
use crate::command::parse::SetArg;
use crate::config::ConfigFile;
use crate::input::command::{Command, Register};
use crate::input::key::Key;
use crate::model::{Direction, EditOp, Group, NodeId, Title};
use crate::view::ViewKind;

/// How a status-bar message is meant.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Tone {
    /// Something to know.
    Info,
    /// Something got done.
    Done,
    /// Something didn't work.
    Problem,
}

/// A message for the status bar.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Message {
    pub text: String,
    pub tone: Tone,
}

/// "1 node", "3 nodes".
pub fn nodes(count: usize) -> String {
    if count == 1 { "1 node".to_string() } else { format!("{count} nodes") }
}

impl Message {
    pub fn info(text: impl Into<String>) -> Message {
        Message { text: text.into(), tone: Tone::Info }
    }

    pub fn done(text: impl Into<String>) -> Message {
        Message { text: text.into(), tone: Tone::Done }
    }

    pub fn problem(text: impl Into<String>) -> Message {
        Message { text: text.into(), tone: Tone::Problem }
    }

    /// Several messages in one, with ` · ` between them: a problem if one of
    /// them is. `None` when there are none.
    pub fn joined(messages: Vec<Message>) -> Option<Message> {
        let problem = messages.iter().any(|message| message.tone == Tone::Problem);
        let tone = if problem { Tone::Problem } else { messages.first()?.tone };
        let texts: Vec<&str> = messages.iter().map(|message| message.text.as_str()).collect();
        Some(Message { text: texts.join(" · "), tone })
    }
}

/// Where the cursor goes after an edit.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CursorAfter {
    /// Where it is (or to the root, if its node is gone).
    Stay,
    /// To the node the edit added.
    Added,
    /// To this node.
    To(NodeId),
}

/// What happens to a document and its cursor.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum DocAction {
    /// Move the cursor. A `jump` is one that `''` can come back from.
    MoveCursor {
        to: NodeId,
        jump: bool,
    },
    /// Change the document, as one undo step (or as part of its group's).
    /// The op is boxed because it can hold whole nodes, which would make
    /// every action that size.
    Edit {
        op: Box<EditOp>,
        cursor: CursorAfter,
        group: Option<Group>,
    },
    Undo(u32),
    Redo(u32),
    SetMark(char),
    /// Go to a mark; `'` and `` ` `` go back to before the last jump.
    JumpToMark(char),
    /// Take back the group's undo step, if it's the newest, leaving nothing
    /// to redo: Esc in connect mode.
    Cancel(Group),
}

/// What happens around the documents.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum AppAction {
    /// Start editing the cursor's title, tags or body.
    StartEdit(StartEdit),
    /// The text edit is done: back to normal mode, or to the `K` card the
    /// body was edited in.
    EndEdit,
    /// Put the text cursor here, in the text being edited (a click).
    TextCursor(usize),
    /// Visual mode, `V` (`branches`) or `v`; in visual mode, switches
    /// between the two.
    Visual {
        branches: bool,
    },
    /// In visual mode: the cursor goes to the other end (`o`).
    SwapEnds,
    /// A node into the selection, or out of it (a Ctrl+click).
    ToggleSelected(NodeId),
    /// Nodes into the selection (a Ctrl+drag).
    SelectAlso(Vec<NodeId>),
    /// Move mode: hjkl moves the cursor's branch, or these nodes (a
    /// selection's).
    EnterMoveMode(Vec<NodeId>),
    /// In move mode: the whole branch, or just the node.
    ToggleWhole,
    /// Connect mode (`C`): from the cursor's node, or from these (a
    /// selection's).
    EnterConnectMode(Vec<NodeId>),
    /// Back to connect mode, from a picker it opened.
    ResumeConnect(Connect),
    /// Enter or `gf` on a portal: through it, to its document's root.
    FollowPortal(NodeId),
    /// `:portal`: a portal under the cursor's node, to the document at the
    /// path typed (a new document when nothing's there).
    NewPortal(String),
    /// `gu`: up to the portals that lead to this document; `list`
    /// (`:backlinks`) lists them even when there's just one.
    GoUp {
        list: bool,
    },
    /// Back to normal mode.
    LeaveMode,
    OpenCommandLine,
    /// The command line, with this typed already: a `:` command from the
    /// help that needs more.
    CommandLineWith(String),
    /// A command line, run as if typed (without its `:`).
    RunLine(String),
    /// A command, run as if its keys were typed: the help and the menu run
    /// commands this way.
    Run(Command),
    /// Keys, as if typed: for a key that waits for more (`m` waits for a
    /// mark's letter).
    Type(Vec<Key>),
    /// Keep nodes in a register (`yy`, and before a delete): exactly
    /// `nodes`, or (`branches`) each with its whole branch.
    Yank {
        register: Option<Register>,
        nodes: Vec<NodeId>,
        branches: bool,
    },
    /// Paste what a register holds (`p`, `P`): its nodes, or its text
    /// made into nodes, `times` copies.
    Paste {
        register: Option<Register>,
        at: PasteAt,
        times: u32,
    },
    /// A value was picked in a picker: `.` can put it on another node.
    Picked(Look),
    /// Focus mode: Open branches act like Auto ones.
    ToggleFocus,
    ToggleWhichKey,
    /// Change a setting.
    Set(SetArg),

    // Popups.
    /// Every key and command, with this already searched for.
    OpenHelp(String),
    /// `/`: the search.
    OpenSearch,
    /// A search went somewhere: `n` and `N` go on with it.
    Searched(String),
    /// `Ctrl-o` (`back`) and `Ctrl-i`: through the focused pane's jump list.
    Travel {
        back: bool,
        times: u32,
    },
    /// `n` and `N`: the next or previous match of the last search.
    FindAgain {
        forward: bool,
        times: u32,
    },
    /// `:find`: straight to the best match.
    Find(String),
    /// A capital mark on the cursor's node (`mA`).
    SetFileMark(char),
    /// To a capital mark, in any document (`'A`).
    JumpToFileMark(char),
    /// To a place from the jump list (`:jumps`).
    GoToPlace(Place),
    /// `:marks`, `:jumps` and `:registers`.
    OpenMarks,
    OpenJumps,
    OpenRegisters,
    /// `gd` on a node with several cross-links: which one to follow.
    OpenLinks,
    /// The cursor's body in a card beside it.
    OpenCard,
    OpenPicker(PickKind),
    /// The right-click menu, at a cell on the screen.
    OpenMenu {
        what: MenuFor,
        col: u16,
        row: u16,
    },

    // Panes and documents.
    /// Split the focused pane: the new pane shows `view`, or the same view.
    Split {
        arrange: Arrange,
        view: Option<ViewKind>,
    },
    FocusPane(Direction),
    NextPane,
    /// Close the focused pane (`:q`, `ZZ`, `Ctrl-w c`). The last one quits,
    /// unless a document has unsaved changes; `force` (`:q!`) quits anyway.
    ClosePane {
        force: bool,
    },
    OnlyPane,
    EqualizePanes,
    /// The focused pane shows another view.
    ShowView(ViewKind),
    SwitchDocument(DocumentChoice),

    // Files.
    /// `:config`: the config files, to open one in the editor.
    OpenConfig,
    /// Open a config file in the editor (made first if it isn't there).
    EditConfig(ConfigFile),
    /// Save (`:w`, `:x`, `:wa`).
    Save(SaveWhich),
    /// Open a document in the focused pane (`:e`), from a path as typed:
    /// relative to the focused document's folder, `~` for the home folder.
    /// No path reads the focused document again from its file; `force`
    /// (`:e!`) drops unsaved changes to do it.
    Edit {
        path: Option<String>,
        force: bool,
    },
    /// Make a new document next to the focused one, and show it (`:new`).
    NewDocument(Option<Title>),
    /// Close the focused document (`:bd`); `force` drops unsaved changes.
    CloseDocument {
        force: bool,
    },
    /// A file changed outside cumulus while its document had unsaved
    /// changes here: which version to keep.
    Resolve {
        buffer: BufferId,
        keep: Keep,
    },

    /// Quit cumulus (`:qa`): not while a document has unsaved changes,
    /// unless `force` (`:qa!`).
    Quit {
        force: bool,
    },
    Say(Message),
}

/// Where `p` and `P` paste, from the cursor's node (the user's pick after
/// trying part 8c: `p` pastes under the node, as `a` adds).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum PasteAt {
    /// Its last children (`p`).
    Child,
    /// Its next siblings, below it, where `o` adds one (`P`).
    Sibling,
}

/// What `:w` and its kin save.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SaveWhich {
    /// The focused document, changed or not (`:w`).
    This,
    /// The focused document, if it has unsaved changes (`:x`, `ZZ`).
    IfChanged,
    /// Every document with unsaved changes (`:wa`).
    All,
}

/// Which version of a document to keep when its file changed outside
/// cumulus while it had unsaved changes here.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Keep {
    /// The one on screen: it's saved over the file.
    Mine,
    /// The file's: it takes the place of the one on screen (`u` brings that
    /// back).
    Theirs,
}

/// Which document the focused pane switches to.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum DocumentChoice {
    Next,
    Previous,
    /// The open document listed at this place (the documents picker).
    At(usize),
    /// The open document with this name (`:b`).
    Named(String),
}

/// Anything views, keys and the command line ask for.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Action {
    Doc(DocAction),
    App(AppAction),
}

impl Action {
    /// Move the cursor to a node.
    pub fn cursor(to: NodeId) -> Action {
        Action::Doc(DocAction::MoveCursor { to, jump: false })
    }

    /// Jump to a node: `''` comes back.
    pub fn jump(to: NodeId) -> Action {
        Action::Doc(DocAction::MoveCursor { to, jump: true })
    }

    /// Change the document, as one undo step; the cursor stays.
    pub fn edit(op: EditOp) -> Action {
        Action::Doc(DocAction::Edit { op: Box::new(op), cursor: CursorAfter::Stay, group: None })
    }

    /// Change the document, as one undo step, then move the cursor.
    pub fn edit_then(op: EditOp, cursor: CursorAfter) -> Action {
        Action::Doc(DocAction::Edit { op: Box::new(op), cursor, group: None })
    }

    /// Change the document as part of a group's undo step.
    pub fn edit_in(op: EditOp, group: Group) -> Action {
        Action::Doc(DocAction::Edit { op: Box::new(op), cursor: CursorAfter::Stay, group: Some(group) })
    }

    /// Show a message.
    pub fn say(message: Message) -> Action {
        Action::App(AppAction::Say(message))
    }
}