feat: add flag for reading specified puzzle part

Add a `--part` flag in the `read` subcommand to display/read the
specified part of the puzzle.

When part 1 is included in display (either by directly specifying
`--part 1`, or by not specifying `--part` flag which defaults to both
part 1 & 2), the `--- Part One ---` subheader is added in the output.
This makes display consistent with the output for part 2
(`--- Part Two ---`, which is included by default), and adds better
indicator for the puzzle sections.

Fixes: #27

aoc-client/src/lib.rs

@@ -84,8 +84,8 @@ pub enum AocError {
     #[error("{0} is not a valid Advent of Code day")]
     InvalidPuzzleDay(PuzzleDay),
 
-    #[error("Puzzle {0} of {1} is still locked")]
-    LockedPuzzle(PuzzleDay, PuzzleYear),
+    #[error("Puzzle {0} part {1} of {2} is still locked")]
+    LockedPuzzle(PuzzleDay, PuzzlePart, PuzzleYear),
 
     #[error("Session cookie file not found in home or config directory")]
     SessionFileNotFound,
@@ -167,7 +167,7 @@ impl AocClient {
         if self.day_unlocked() {
             Ok(())
         } else {
-            Err(AocError::LockedPuzzle(self.day, self.year))
+            Err(AocError::LockedPuzzle(self.day, PuzzlePart::PartOne, self.year))
         }
     }
 
@@ -296,9 +296,31 @@ impl AocClient {
         Ok(())
     }
 
-    pub fn show_puzzle(&self) -> AocResult<()> {
+    pub fn show_puzzle(&self, part: Option<&str>) -> AocResult<()> {
         let puzzle_html = self.get_puzzle_html()?;
-        println!("\n{}", self.html2text(&puzzle_html));
+
+        // Grabs the header of the format: `--- Day Foo: Bar ---`
+        let header_end = puzzle_html
+            .match_indices("---")
+            .nth(1)
+            .map(|(start, _)| start + 3)
+            .unwrap();
+        // Grabs content range of our puzzle of interest.
+        let body_range = match (part, puzzle_html.find("--- Part Two ---")) {
+            (Some("1"), Some(p2_start)) => header_end..p2_start,
+            (Some("1"), None) | (None, _) => header_end..puzzle_html.len(),
+            (Some("2"), Some(p2_start)) => p2_start..puzzle_html.len(),
+            (Some("2"), None) => return Err(AocError::LockedPuzzle(self.day, PuzzlePart::PartTwo, self.year)),
+            _ => return Err(AocError::InvalidPuzzlePart),
+        };
+        let mut display = puzzle_html[..header_end].to_owned() + "<br>";
+        if matches!(part, Some("1") | None) {
+            // Insert `Part One` banner along with header.
+            display.push_str("--- Part One ---");
+        }
+        display.push_str(&puzzle_html[body_range]);
+
+        println!("\n{}", self.html2text(&display));
         Ok(())
     }
 

src/args.rs

@@ -89,7 +89,11 @@ pub enum Command {
 
     /// Read puzzle statement (the default command)
     #[command(visible_alias = "r")]
-    Read,
+    Read {
+        /// Puzzle part
+        #[arg(long, value_parser = ["1", "2"])]
+        part: Option<String>,
+    },
 
     /// Submit puzzle answer
     #[command(visible_alias = "s")]

src/main.rs

@@ -109,6 +109,7 @@ fn run(args: &Args, client: AocClient) -> AocResult<()> {
         Some(Command::PrivateLeaderboard { leaderboard_id }) => {
             client.show_private_leaderboard(*leaderboard_id)
         }
-        _ => client.show_puzzle(),
+        Some(Command::Read { part }) => client.show_puzzle(part.as_deref()),
+        _ => client.show_puzzle(None),
     }
 }