codecrafters submit [skip ci]

2 files changed, 155 insertions, 3 deletions

diff --git a/src/main.zig b/src/main.zig
index 4394d13..6e1f547 100755
--- a/src/main.zig
+++ b/src/main.zig
@@ -48,9 +48,36 @@ pub fn main() !void {
         const select_len: usize = 6; // length of "SELECT" or "select"
         const column_part = std.mem.trim(u8, args[2][select_len..from_idx], " \t\n");
 
-        // Extract table name (after FROM)
+        // Find WHERE clause if it exists
+        const where_idx_upper = std.mem.indexOf(u8, args[2][from_idx..], "WHERE");
+        const where_idx_lower = std.mem.indexOf(u8, args[2][from_idx..], "where");
+        const where_idx_rel = where_idx_upper orelse where_idx_lower;
+
+        // Extract table name (after FROM, before WHERE if exists)
         const from_end = from_idx + 4; // length of "FROM"
-        const table_name = std.mem.trim(u8, args[2][from_end..], " \t\n");
+        const table_end = if (where_idx_rel) |idx| from_idx + idx else args[2].len;
+        const table_name = std.mem.trim(u8, args[2][from_end..table_end], " \t\n");
+
+        // Parse WHERE clause if it exists
+        var where_column: ?[]const u8 = null;
+        var where_value: ?[]const u8 = null;
+        if (where_idx_rel) |idx| {
+            const where_start = from_idx + idx + 5; // +5 for "WHERE"
+            const where_clause = std.mem.trim(u8, args[2][where_start..], " \t\n");
+
+            // Parse WHERE clause: "column = 'value'"
+            if (std.mem.indexOf(u8, where_clause, "=")) |eq_idx| {
+                where_column = std.mem.trim(u8, where_clause[0..eq_idx], " \t\n");
+                var value_part = std.mem.trim(u8, where_clause[eq_idx + 1 ..], " \t\n");
+
+                // Remove quotes from value
+                if (value_part.len >= 2 and value_part[0] == '\'' and value_part[value_part.len - 1] == '\'') {
+                    where_value = value_part[1 .. value_part.len - 1];
+                } else {
+                    where_value = value_part;
+                }
+            }
+        }
 
         // Check if this is COUNT(*)
         if (std.mem.indexOf(u8, column_part, "count(") != null or std.mem.indexOf(u8, column_part, "COUNT(") != null) {
@@ -75,6 +102,12 @@ pub fn main() !void {
             // Get the table's root page
             const rootpage = try schema.getRootpage(allocator, &file, page_size, table_name);
 
+            // Get WHERE column index if present
+            var where_column_idx: ?usize = null;
+            if (where_column) |col| {
+                where_column_idx = try schema.parseColumnIndex(create_sql, col);
+            }
+
             if (column_list.items.len == 1) {
                 // Single column query
                 const column_idx = try schema.parseColumnIndex(create_sql, column_list.items[0]);
@@ -89,7 +122,7 @@ pub fn main() !void {
                     try column_indices.append(allocator, idx);
                 }
 
-                try schema.readTableRowsMultiColumn(allocator, &file, page_size, rootpage, column_indices.items, stdout);
+                try schema.readTableRowsMultiColumnWhere(allocator, &file, page_size, rootpage, column_indices.items, where_column_idx, where_value, stdout);
             }
         }
     } else {
diff --git a/src/schema.zig b/src/schema.zig
index 5a6d60b..fce45ff 100644
--- a/src/schema.zig
+++ b/src/schema.zig
@@ -373,3 +373,122 @@ pub fn readTableRowsMultiColumn(allocator: std.mem.Allocator, file: *std.fs.File
         try stdout.print("\n", .{});
     }
 }
+
+pub fn readTableRowsMultiColumnWhere(allocator: std.mem.Allocator, file: *std.fs.File, page_size: u16, rootpage: u32, column_indices: []const usize, where_column_idx: ?usize, where_value: ?[]const u8, stdout: anytype) !void {
+    if (rootpage == 0) return;
+
+    const page_offset = (rootpage - 1) * @as(u64, page_size);
+    var page_data = try allocator.alloc(u8, page_size);
+    defer allocator.free(page_data);
+
+    _ = try file.seekTo(page_offset);
+    _ = try file.read(page_data);
+
+    const page_type = page_data[0];
+    if (page_type != 0x0d) return;
+
+    const num_cells = std.mem.readInt(u16, page_data[3..5], .big);
+
+    var cell_pointers = try allocator.alloc(u16, num_cells);
+    defer allocator.free(cell_pointers);
+
+    for (0..num_cells) |i| {
+        const offset = 8 + i * 2;
+        const cell_ptr_bytes = page_data[offset .. offset + 2];
+        cell_pointers[i] = std.mem.readInt(u16, cell_ptr_bytes[0..2], .big);
+    }
+
+    for (0..num_cells) |i| {
+        const cell_data = page_data[cell_pointers[i]..];
+
+        var parsed = varint.parse(cell_data);
+        var pos = parsed.len;
+
+        parsed = varint.parse(cell_data[pos..]);
+        pos += parsed.len;
+
+        const record_data = cell_data[pos..];
+        parsed = varint.parse(record_data);
+        const header_size = parsed.value;
+        var header_pos = parsed.len;
+
+        var serial_types = std.ArrayList(u64){};
+        defer serial_types.deinit(allocator);
+
+        while (header_pos < header_size) {
+            parsed = varint.parse(record_data[header_pos..]);
+            try serial_types.append(allocator, parsed.value);
+            header_pos += parsed.len;
+        }
+
+        // Check WHERE condition if present
+        if (where_column_idx) |where_idx| {
+            if (where_value) |expected_value| {
+                // Calculate position for WHERE column
+                var where_body_pos: usize = header_size;
+                for (0..where_idx) |col| {
+                    if (col >= serial_types.items.len) break;
+                    const st = serial_types.items[col];
+                    if (st >= 13 and (st % 2) == 1) {
+                        where_body_pos += (st - 13) / 2;
+                    } else if (st >= 1 and st <= 6) {
+                        const int_result = record.readInt(record_data[where_body_pos..], st);
+                        where_body_pos += int_result.len;
+                    }
+                }
+
+                // Read WHERE column value
+                var matches = false;
+                if (where_idx < serial_types.items.len) {
+                    const st = serial_types.items[where_idx];
+                    if (st >= 13 and (st % 2) == 1) {
+                        const str_result = record.readString(record_data[where_body_pos..], st);
+                        matches = std.mem.eql(u8, str_result.value, expected_value);
+                    } else if (st >= 1 and st <= 6) {
+                        const int_result = record.readInt(record_data[where_body_pos..], st);
+                        // Try to parse expected_value as integer
+                        const expected_int = std.fmt.parseInt(i64, expected_value, 10) catch 0;
+                        matches = int_result.value == expected_int;
+                    }
+                }
+
+                // Skip this row if it doesn't match
+                if (!matches) continue;
+            }
+        }
+
+        // For each requested column
+        for (column_indices, 0..) |column_idx, col_num| {
+            // Calculate position for this column
+            var body_pos: usize = header_size;
+            for (0..column_idx) |col| {
+                if (col >= serial_types.items.len) break;
+                const st = serial_types.items[col];
+                if (st >= 13 and (st % 2) == 1) {
+                    body_pos += (st - 13) / 2;
+                } else if (st >= 1 and st <= 6) {
+                    const int_result = record.readInt(record_data[body_pos..], st);
+                    body_pos += int_result.len;
+                }
+            }
+
+            // Print separator if not first column
+            if (col_num > 0) {
+                try stdout.print("|", .{});
+            }
+
+            // Read and print the column value
+            if (column_idx < serial_types.items.len) {
+                const st = serial_types.items[column_idx];
+                if (st >= 13 and (st % 2) == 1) {
+                    const str_result = record.readString(record_data[body_pos..], st);
+                    try stdout.print("{s}", .{str_result.value});
+                } else if (st >= 1 and st <= 6) {
+                    const int_result = record.readInt(record_data[body_pos..], st);
+                    try stdout.print("{}", .{int_result.value});
+                }
+            }
+        }
+        try stdout.print("\n", .{});
+    }
+}