1 files changed, 174 insertions, 0 deletions
diff --git a/src/watch/state.rs b/src/watch/state.rs
new file mode 100644
index 0000000..78af30a
--- /dev/null
+++ b/src/watch/state.rs
@@ -0,0 +1,174 @@
+use anyhow::Result;
+use crossterm::{
+    style::{style, Stylize},
+    terminal,
+};
+use std::io::{self, StdoutLock, Write};
+
+use crate::{
+    app_state::{AppState, ExercisesProgress},
+    clear_terminal,
+    exercise::{RunnableExercise, OUTPUT_CAPACITY},
+    progress_bar::progress_bar,
+    terminal_link::TerminalFileLink,
+};
+
+#[derive(PartialEq, Eq)]
+enum DoneStatus {
+    DoneWithSolution(String),
+    DoneWithoutSolution,
+    Pending,
+}
+
+pub struct WatchState<'a> {
+    writer: StdoutLock<'a>,
+    app_state: &'a mut AppState,
+    output: Vec<u8>,
+    show_hint: bool,
+    done_status: DoneStatus,
+    manual_run: bool,
+}
+
+impl<'a> WatchState<'a> {
+    pub fn new(app_state: &'a mut AppState, manual_run: bool) -> Self {
+        let writer = io::stdout().lock();
+
+        Self {
+            writer,
+            app_state,
+            output: Vec::with_capacity(OUTPUT_CAPACITY),
+            show_hint: false,
+            done_status: DoneStatus::Pending,
+            manual_run,
+        }
+    }
+
+    #[inline]
+    pub fn into_writer(self) -> StdoutLock<'a> {
+        self.writer
+    }
+
+    pub fn run_current_exercise(&mut self) -> Result<()> {
+        self.show_hint = false;
+
+        let success = self
+            .app_state
+            .current_exercise()
+            .run_exercise(&mut self.output, self.app_state.target_dir())?;
+        if success {
+            self.done_status =
+                if let Some(solution_path) = self.app_state.current_solution_path()? {
+                    DoneStatus::DoneWithSolution(solution_path)
+                } else {
+                    DoneStatus::DoneWithoutSolution
+                };
+        } else {
+            self.app_state
+                .set_pending(self.app_state.current_exercise_ind())?;
+
+            self.done_status = DoneStatus::Pending;
+        }
+
+        self.render()
+    }
+
+    pub fn handle_file_change(&mut self, exercise_ind: usize) -> Result<()> {
+        // Don't skip exercises on file changes to avoid confusion from missing exercises.
+        // Skipping exercises must be explicit in the interactive list.
+        // But going back to an earlier exercise on file change is fine.
+        if self.app_state.current_exercise_ind() < exercise_ind {
+            return Ok(());
+        }
+
+        self.app_state.set_current_exercise_ind(exercise_ind)?;
+        self.run_current_exercise()
+    }
+
+    /// Move on to the next exercise if the current one is done.
+    pub fn next_exercise(&mut self) -> Result<ExercisesProgress> {
+        if self.done_status == DoneStatus::Pending {
+            return Ok(ExercisesProgress::CurrentPending);
+        }
+
+        self.app_state.done_current_exercise(&mut self.writer)
+    }
+
+    fn show_prompt(&mut self) -> io::Result<()> {
+        self.writer.write_all(b"\n")?;
+
+        if self.manual_run {
+            write!(self.writer, "{}:run / ", 'r'.bold())?;
+        }
+
+        if self.done_status != DoneStatus::Pending {
+            write!(self.writer, "{}:{} / ", 'n'.bold(), "next".underlined())?;
+        }
+
+        if !self.show_hint {
+            write!(self.writer, "{}:hint / ", 'h'.bold())?;
+        }
+
+        write!(self.writer, "{}:list / {}:quit ? ", 'l'.bold(), 'q'.bold())?;
+
+        self.writer.flush()
+    }
+
+    pub fn render(&mut self) -> Result<()> {
+        // Prevent having the first line shifted if clearing wasn't successful.
+        self.writer.write_all(b"\n")?;
+
+        clear_terminal(&mut self.writer)?;
+
+        self.writer.write_all(&self.output)?;
+        self.writer.write_all(b"\n")?;
+
+        if self.show_hint {
+            writeln!(
+                self.writer,
+                "{}\n{}\n",
+                "Hint".bold().cyan().underlined(),
+                self.app_state.current_exercise().hint,
+            )?;
+        }
+
+        if self.done_status != DoneStatus::Pending {
+            writeln!(
+                self.writer,
+                "{}\n",
+                "Exercise done ✓
+When you are done experimenting, enter `n` to move on to the next exercise 🦀"
+                    .bold()
+                    .green(),
+            )?;
+        }
+
+        if let DoneStatus::DoneWithSolution(solution_path) = &self.done_status {
+            writeln!(
+                self.writer,
+                "A solution file can be found at {}\n",
+                style(TerminalFileLink(solution_path)).underlined().green(),
+            )?;
+        }
+
+        let line_width = terminal::size()?.0;
+        let progress_bar = progress_bar(
+            self.app_state.n_done(),
+            self.app_state.exercises().len() as u16,
+            line_width,
+        )?;
+        writeln!(
+            self.writer,
+            "{progress_bar}Current exercise: {}",
+            self.app_state.current_exercise().terminal_link(),
+        )?;
+
+        self.show_prompt()?;
+
+        Ok(())
+    }
+
+    pub fn show_hint(&mut self) -> Result<()> {
+        self.show_hint = true;
+        self.render()
+    }
+}