From 3d038ab84e30457d4b5dbd13ed2cc25f2d563683 Mon Sep 17 00:00:00 2001
From: Joel Therrien <joel@joeltherrien.ca>
Date: Tue, 1 Sep 2020 18:16:17 -0700
Subject: [PATCH] WIP - Add initial code using arrays.

---
 src/main.rs | 160 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)
 create mode 100644 src/main.rs

diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..449cb89
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,160 @@
+use std::borrow::BorrowMut;
+
+enum CellValue {
+    FIXED(u8),
+    GUESS(u8),
+    UNKNOWN(Vec<u8>)
+}
+
+struct Cell(CellValue);
+
+struct Grid<'a> {
+    rows: Vec<[&'a mut Cell; 9]>, // Read from top to bottom
+    columns: Vec<[&'a Cell; 9]>, // Left to right
+    sections: Vec<[&'a Cell; 9]> // left to right, top to bottom
+}
+
+impl<'a> Grid<'a> {
+    fn get(&self, r: usize, c: usize) -> Option<&Cell> {
+        let row = self.rows.get(r)?;
+        let cell = &row[c];
+
+        return Some(&cell);
+    }
+
+    fn get_mut(&'a mut self, r: usize, c: usize) -> Option<&'a mut Cell> {
+        let row : &'a mut [&'a mut Cell; 9] = self.rows.get_mut(r)?;
+        let cell : &'a mut Cell = row[c].borrow_mut();
+
+        return Some(cell);
+
+    }
+
+    fn print(&self) {
+        for r in 0..9 {
+            if (r & 3 == 0) && (r > 0) {
+                println!("---+---+---");
+            }
+
+            for c in 0..9 {
+                if (c % 3 == 0) && (c > 0) {
+                    print!("|");
+                }
+
+                let value = &self.get(r, c).unwrap().0;
+                match value {
+                    CellValue::FIXED(x) => print!("{}", x),
+                    _ => print!(" ")
+                };
+
+            }
+
+            print!("\n");
+        }
+    }
+}
+
+fn main() {
+    println!("Hello, world!");
+    let grid = retrieve_grid();
+    grid.print();
+
+}
+
+fn empty_grid<'a>() -> Grid<'a> {
+    let mut placeholder_cell : Cell = Cell(CellValue::FIXED(0));
+
+    // Rows first; we need to create cells for all of them
+    let mut rows : Vec<[&'a mut Cell; 9]> = Vec::new();
+    for _r in 0..9 {
+        let mut new_row : [&'a mut Cell; 9] = [&mut placeholder_cell; 9];
+        for i in 0..9{
+            new_row[i] = &mut initial_empty_cell();
+        }
+
+        rows.push(new_row);
+    }
+
+    // Columns next; now we have to retrieve the cells from the different rows
+    let mut columns : Vec<[&'a Cell; 9]> = Vec::new();
+    for c in 0..9 {
+        let mut new_column : [&'a Cell; 9] = [&placeholder_cell; 9];
+        for r in 0..9{
+            new_column[r] = rows.get(r).unwrap()[c]; // TODO - improve performance by using get_unchecked
+        }
+        columns.push(new_column);
+    }
+
+    // Sections next; now we have to retrieve the cells from different rows and columns
+    // We read sections from left to right, top to bottom
+    let mut sections : Vec<[&'a Cell; 9]> = Vec::new();
+    for r in 0..3 {
+        for c in 0..3 {
+            let mut new_section : [&'a Cell; 9] = [&placeholder_cell; 9];
+
+            for internal_r in 0..3 {
+                let global_r = 3*r + internal_r;
+
+                for internal_c in 0..3 {
+                    let global_c = 3*c + internal_c;
+                    let index = 3*internal_c + internal_r;
+
+                    new_section[index] = rows.get(global_r).unwrap()[global_c];
+                }
+            }
+
+            sections.push(new_section);
+
+        }
+    }
+
+    return Grid {rows, columns, sections};
+}
+
+fn initial_empty_cell() -> Cell {
+    return Cell(CellValue::UNKNOWN(vec![1, 2, 3, 4, 5, 6, 7, 8, 9]));
+}
+
+/**
+    For now this is a stub with a pre-programmed grid; later I'll add functionality to read a CSV file
+ */
+fn retrieve_grid<'a>() -> Grid<'a> {
+    let mut grid = empty_grid();
+
+    grid.get_mut(0, 4).unwrap().0 = CellValue::FIXED(8);
+    grid.get_mut(0, 5).unwrap().0 = CellValue::FIXED(5);
+    grid.get_mut(0, 6).unwrap().0 = CellValue::FIXED(6);
+
+    grid.get_mut(2, 3).unwrap().0 = CellValue::FIXED(9);
+    grid.get_mut(2, 4).unwrap().0 = CellValue::FIXED(4);
+    grid.get_mut(2, 5).unwrap().0 = CellValue::FIXED(3);
+    grid.get_mut(2, 6).unwrap().0 = CellValue::FIXED(5);
+    grid.get_mut(2, 7).unwrap().0 = CellValue::FIXED(7);
+
+    grid.get_mut(3, 0).unwrap().0 = CellValue::FIXED(8);
+    grid.get_mut(3, 2).unwrap().0 = CellValue::FIXED(2);
+    grid.get_mut(3, 3).unwrap().0 = CellValue::FIXED(6);
+    grid.get_mut(3, 4).unwrap().0 = CellValue::FIXED(7);
+    grid.get_mut(3, 5).unwrap().0 = CellValue::FIXED(4);
+    grid.get_mut(3, 6).unwrap().0 = CellValue::FIXED(9);
+
+    grid.get_mut(4, 4).unwrap().0 = CellValue::FIXED(9);
+    grid.get_mut(4, 8).unwrap().0 = CellValue::FIXED(5);
+
+    grid.get_mut(5, 1).unwrap().0 = CellValue::FIXED(6);
+    grid.get_mut(5, 6).unwrap().0 = CellValue::FIXED(2);
+
+    grid.get_mut(6, 1).unwrap().0 = CellValue::FIXED(8);
+    grid.get_mut(6, 8).unwrap().0 = CellValue::FIXED(2);
+
+    grid.get_mut(7, 3).unwrap().0 = CellValue::FIXED(7);
+    grid.get_mut(7, 5).unwrap().0 = CellValue::FIXED(6);
+    grid.get_mut(7, 7).unwrap().0 = CellValue::FIXED(5);
+    grid.get_mut(7, 8).unwrap().0 = CellValue::FIXED(4);
+
+    grid.get_mut(8, 2).unwrap().0 = CellValue::FIXED(7);
+    grid.get_mut(8, 3).unwrap().0 = CellValue::FIXED(4);
+
+
+    return grid;
+}