//! Editor commands — the values key bindings map to.
//!
//! Kept distinct from [`crate::action::Action`], which is application-level
//! (tick, render, resize). A binding names a `Command`; the buffer executes it.
//! `Quit` and `Suspend` appear here because the `Global` keymap is expressed in
//! the same table and must be able to name them.

use serde::{Deserialize, Serialize};
use strum::Display;

/// MJB-LLR-157: one unit variant per bound editor command, deserialized from
/// the variant name so a TOML value like `"MoveCharLeft"` resolves directly.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Display, Serialize, Deserialize)]
pub enum Command {
    // --- Application (reachable from the `global` keymap) ---
    Quit,
    Suspend,

    // --- Mode switching ---
    NormalMode,
    InsertMode,
    SelectMode,
    CommandMode,

    // --- Character and line motion (MJB-HLR-006) ---
    MoveCharLeft,
    MoveCharRight,
    MoveLineUp,
    MoveLineDown,

    // --- Word motion; these produce selections (MJB-HLR-007) ---
    MoveNextWordStart,
    MovePrevWordStart,
    MoveNextWordEnd,
    MoveNextLongWordStart,
    MovePrevLongWordStart,
    MoveNextLongWordEnd,

    // --- Extending variants, used by select mode ---
    ExtendCharLeft,
    ExtendCharRight,
    ExtendLineUp,
    ExtendLineDown,
    ExtendNextWordStart,
    ExtendPrevWordStart,
    ExtendNextWordEnd,

    // --- Goto (MJB-HLR-008) ---
    GotoFileStart,
    GotoLastLine,
    GotoLineStart,
    GotoLineEnd,
    GotoFirstNonWhitespace,

    // --- Selection manipulation ---
    ExtendLineBelow,
    CollapseSelection,
    FlipSelections,
    SelectAll,

    // --- Entering insert mode (MJB-HLR-009) ---
    AppendMode,
    InsertAtLineStart,
    InsertAtLineEnd,
    OpenBelow,
    OpenAbove,

    // --- Modification (MJB-HLR-010) ---
    DeleteSelection,
    ChangeSelection,
    InsertNewline,
    InsertTab,
    DeleteCharBackward,
    DeleteCharForward,
    DeleteWordBackward,
    KillToLineStart,

    // --- Undo / redo (MJB-HLR-011) ---
    Undo,
    Redo,

    // --- Scrolling and paging (MJB-HLR-013) ---
    PageCursorHalfUp,
    PageCursorHalfDown,
    PageUp,
    PageDown,

    // --- Command line (MJB-HLR-016) ---
    CommandSubmit,
    CommandBackspace,
}

#[cfg(test)]
mod tests {
    use super::*;

    /// MJB-LLR-157: a TOML value naming a variant deserializes to it, which is
    /// what makes the keymap config-driven.
    #[test]
    fn mjb_llr_157_deserializes_from_the_variant_name() {
        let cmd: Command = serde_json_free_parse("MoveCharLeft");
        assert_eq!(cmd, Command::MoveCharLeft);
        assert_eq!(serde_json_free_parse("Undo"), Command::Undo);
        assert_eq!(
            serde_json_free_parse("PageCursorHalfDown"),
            Command::PageCursorHalfDown
        );
    }

    #[test]
    fn mjb_llr_157_unknown_command_name_is_an_error_not_a_panic() {
        let err = toml::from_str::<Wrapper>("cmd = \"NoSuchCommand\"").unwrap_err();
        assert!(
            err.to_string().contains("NoSuchCommand"),
            "error must name the offending value, got: {err}"
        );
    }

    #[test]
    fn mjb_llr_157_display_round_trips_through_deserialization() {
        for cmd in [
            Command::Quit,
            Command::GotoFileStart,
            Command::DeleteSelection,
            Command::CommandSubmit,
        ] {
            assert_eq!(
                serde_json_free_parse(&cmd.to_string()),
                cmd,
                "{cmd} must round-trip"
            );
        }
    }

    #[derive(Debug, serde::Deserialize)]
    struct Wrapper {
        cmd: Command,
    }

    /// Parse a bare command name the way the keymap table does.
    fn serde_json_free_parse(name: &str) -> Command {
        let doc = format!("cmd = \"{name}\"");
        toml::from_str::<Wrapper>(&doc)
            .unwrap_or_else(|e| panic!("{name} must parse: {e}"))
            .cmd
    }
}