From a1e913e617bf6b2637c0cac56adabe980d27387f Mon Sep 17 00:00:00 2001
From: Martin Ashby <martin@ashbysoft.com>
Date: Sat, 3 Dec 2022 10:37:08 +0000
Subject: Days 1-3

---
 src/day2.rs | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 src/day2.rs

(limited to 'src/day2.rs')

diff --git a/src/day2.rs b/src/day2.rs
new file mode 100644
index 0000000..15a99de
--- /dev/null
+++ b/src/day2.rs
@@ -0,0 +1,124 @@
+// Accumulator structure... 
+// parse each line
+
+use simple_error::{SimpleError,bail};
+
+#[derive(PartialEq)]
+enum Move{ Rock, Paper, Scissors }
+enum Res { Win, Draw, Loss }
+
+fn parse_m1(c: char) -> Result<Move, SimpleError> {
+    match c {
+        'A' => Ok(Move::Rock),
+        'B' => Ok(Move::Paper),
+        'C' => Ok(Move::Scissors),
+        _ => bail!("invalid character {}", c)
+    }
+}
+// fn parse_m2(c: char) -> Result<Move, SimpleError> {
+//     match c {
+//         'X' => Ok(Move::Rock),
+//         'Y' => Ok(Move::Paper),
+//         'Z' => Ok(Move::Scissors),
+//        _ => bail!("invalid character {}", c)
+//     }
+// }
+fn parse_req_res(c: char) -> Result<Res, SimpleError> {
+    match c {
+        'X' => Ok(Res::Loss),
+        'Y' => Ok(Res::Draw),
+        'Z' => Ok(Res::Win),
+        _ => bail!("invalid character {}", c)
+    }
+}
+// fn win(opp: Move, you: Move) -> Res {
+//     match opp {
+//         Move::Rock => match you {
+//             Move::Rock => Res::Draw,
+//             Move::Paper => Res::Win,
+//             Move::Scissors => Res::Loss,
+//         },
+//         Move::Paper => match you {
+//             Move::Rock => Res::Loss,
+//             Move::Paper => Res::Draw,
+//             Move::Scissors => Res::Win,
+//         },
+//         Move::Scissors => match you {
+//             Move::Rock => Res::Win,
+//             Move::Paper => Res::Loss,
+//             Move::Scissors => Res::Draw,
+//         }
+//     }
+// }
+fn calc_req_move(opp: Move, req_res: Res) -> Move {
+    match req_res {
+        Res::Win => match opp {
+            Move::Rock => Move::Paper,
+            Move::Paper => Move::Scissors,
+            Move::Scissors => Move::Rock
+        }
+        Res::Draw => opp,
+        Res::Loss => match opp {
+            Move::Rock => Move::Scissors,
+            Move::Paper => Move::Rock,
+            Move::Scissors => Move::Paper   
+        }
+    }
+}
+
+// fn score(opp: Move, you: Move) -> u32 {
+//     let ms: u32 = match you {
+//         Move::Rock => 1,
+//         Move::Paper => 2,
+//         Move::Scissors => 3,
+//     };
+//     let ws: u32 = match win(opp, you) {
+//         Res::Win => 6,
+//         Res::Draw => 3,
+//         Res::Loss => 0,
+//     };
+//     return ms+ws;
+// }
+fn score(opp: Move, req_res: Res) -> u32 {
+    let ws: u32 = match req_res {
+        Res::Win => 6,
+        Res::Draw => 3,
+        Res::Loss => 0,
+    };
+    let mm = calc_req_move(opp, req_res);
+    let ms: u32 = match mm {
+        Move::Rock => 1,
+        Move::Paper => 2,
+        Move::Scissors => 3,
+    };
+    return ms+ws;
+}
+
+// fn parse_turn(line: &str) -> Result<(Move, Move), SimpleError> {
+//     let mut lc = line.chars();
+//     let e1: SimpleError = SimpleError::new("not enough characters in input!");
+//     let c1 = lc.next().ok_or(e1.clone())?;
+//     lc.next().ok_or(e1.clone())?;
+//     let c2 = lc.next().ok_or(e1.clone())?;
+//     let m_opp = parse_m1(c1)?;
+//     let m_you = parse_m2(c2)?;
+//     Ok((m_opp, m_you))
+// }
+fn parse_turn(line: &str) -> Result<(Move, Res), SimpleError> {
+    let mut lc = line.chars();
+    let e1: SimpleError = SimpleError::new("not enough characters in input!");
+    let c1 = lc.next().ok_or(e1.clone())?;
+    lc.next().ok_or(e1.clone())?;
+    let c2 = lc.next().ok_or(e1.clone())?;
+    let m_opp = parse_m1(c1)?;
+    let req_res = parse_req_res(c2)?;
+    Ok((m_opp, req_res))
+}
+
+pub fn run(input: String) {
+    let score: u32 = input.lines().map(|line| {
+        let (m_opp, m_you) = parse_turn(line).expect("invalid input line!");
+        score(m_opp, m_you)
+    }).sum::<u32>();
+    println!("day 2: {}", score);
+}
\ No newline at end of file
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