initial commit - plug in crossterm and make simple splash screen

Author: samgqroberts

.gitignore

@@ -0,0 +1 @@
+/target

Cargo.lock

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+[package]
+name = "merchant"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+crossterm = "0.26.1"

Cargo.toml

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+use std::{
+    io::{self},
+    time::Duration,
+};
+
+use crossterm::{
+    cursor::{MoveTo, MoveToNextLine},
+    event::{poll, read, Event, KeyCode, KeyModifiers},
+    execute,
+    style::{style, Attribute, Color, PrintStyledContent, Stylize},
+    terminal::{disable_raw_mode, enable_raw_mode, Clear},
+};
+
+struct GameState {
+    initialized: bool,
+}
+
+impl GameState {
+    fn new() -> GameState {
+        GameState { initialized: false }
+    }
+}
+
+fn main_loop(game_state: &mut GameState) -> io::Result<(bool, Option<GameState>)> {
+    // Wait up to 1s for some user event
+    if poll(Duration::from_millis(1_000))? {
+        // Read what even happened from the poll
+        // It's guaranteed that read() won't block if `poll` returns `Ok(true)`
+        match read()? {
+            Event::Key(event) => {
+                // detect exit request
+                if event.modifiers == KeyModifiers::CONTROL && event.code == KeyCode::Char('c') {
+                    return Ok((true, None));
+                }
+                // move forward game state
+                if !game_state.initialized {
+                    // initialize game
+                    execute!(
+                        io::stdout(),
+                        // clear terminal
+                        Clear(crossterm::terminal::ClearType::All),
+                        // reset cursor position to top left
+                        MoveTo(0, 0),
+                        // write out new game state
+                        PrintStyledContent(
+                            "Game has begun."
+                                .with(Color::White)
+                                .on(Color::Red)
+                                .attribute(Attribute::Bold)
+                        ),
+                    )?;
+                    return Ok((false, Some(GameState { initialized: true })));
+                }
+                // user event had no effect
+                Ok((false, None))
+            }
+            _ => Ok((false, None)),
+        }
+    } else {
+        // Timeout expired, no event for 1s
+        Ok((false, None))
+    }
+}
+
+fn main() -> io::Result<()> {
+    // initial splash screen
+    execute!(
+        io::stdout(),
+        // clear terminal
+        Clear(crossterm::terminal::ClearType::All),
+        // reset cursor position to top left
+        MoveTo(0, 0),
+        // write out splash screen
+        PrintStyledContent(
+            "Merchant\n\nNavigate shifting markets and unreliable sources.\n\nBy samgqroberts"
+                .with(Color::Yellow)
+                .on(Color::Blue)
+                .attribute(Attribute::Bold)
+        ),
+        // prompt user
+        MoveToNextLine(2),
+        PrintStyledContent(
+            style("Press any key to begin")
+                .with(Color::Blue)
+                .on(Color::Yellow)
+                .attribute(Attribute::Bold),
+        ),
+    )?;
+    // set terminal into "non-canonical" mode so inputs are captured raw with no interpretation
+    // https://docs.rs/crossterm/0.26.1/crossterm/terminal/index.html#raw-mode
+    enable_raw_mode()?;
+    // start main game loop, with fresh game state
+    let mut game_state = GameState::new();
+    loop {
+        // perform main loop logic, detect and handle potential io error
+        match main_loop(&mut game_state) {
+            Err(e) => {
+                // an error was encountered in main game loop
+                println!("Error: {:?}\r", e);
+            }
+            Ok((should_exit, new_game_state)) => {
+                // main loop may have told us user requested an exit
+                if should_exit {
+                    break;
+                }
+                // main loop may have given back a new game state
+                if let Some(new_game_state) = new_game_state {
+                    game_state = new_game_state
+                }
+            }
+        }
+    }
+    // set terminal back to canonical mode before exiting
+    disable_raw_mode()
+}