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const std = @import("std");
const varint = @import("varint.zig");
const record = @import("record.zig");
const schema = @import("schema.zig");
const tables = @import("tables.zig");
var stdout_buffer: [1024]u8 = undefined;
var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
const stdout = &stdout_writer.interface;
pub fn main() !void {
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
defer _ = gpa.deinit();
const allocator = gpa.allocator();
const args = try std.process.argsAlloc(allocator);
defer std.process.argsFree(allocator, args);
if (args.len < 3) {
std.debug.print("Usage: {s} <database_file_path> <command>\n", .{args[0]});
std.process.exit(1);
}
var file = try std.fs.cwd().openFile(args[1], .{});
defer file.close();
var buf: [2]u8 = undefined;
_ = try file.seekTo(16);
_ = try file.read(&buf);
const page_size = std.mem.readInt(u16, &buf, .big);
if (std.mem.eql(u8, args[2], ".dbinfo")) {
_ = try file.seekTo(103);
_ = try file.read(&buf);
const num_tables = std.mem.readInt(u16, &buf, .big);
try stdout.print("database page size: {}\n", .{page_size});
try stdout.print("number of tables: {}\n", .{num_tables});
} else if (std.mem.eql(u8, args[2], ".tables")) {
try tables.showTables(allocator, &file, page_size, stdout);
} else if (std.mem.startsWith(u8, args[2], "SELECT") or std.mem.startsWith(u8, args[2], "select")) {
// Parse SELECT query: "SELECT column FROM table"
var tokens = std.mem.tokenizeScalar(u8, args[2], ' ');
// Skip "SELECT"
_ = tokens.next();
// Get column name or aggregate function
const column_name = tokens.next() orelse return error.InvalidQuery;
// Skip "FROM" or "from"
_ = tokens.next();
// Get table name
const table_name = tokens.next() orelse return error.InvalidQuery;
// Check if this is COUNT(*)
if (std.mem.indexOf(u8, column_name, "count(") != null or std.mem.indexOf(u8, column_name, "COUNT(") != null) {
const rootpage = try schema.getRootpage(allocator, &file, page_size, table_name);
const row_count = try schema.countRows(allocator, &file, page_size, rootpage);
try stdout.print("{}\n", .{row_count});
} else {
// Get the CREATE TABLE statement to find column order
const create_sql = try schema.getCreateTableSQL(allocator, &file, page_size, table_name);
defer allocator.free(create_sql);
// Find the column index
const column_idx = try schema.parseColumnIndex(create_sql, column_name);
// Get the table's root page
const rootpage = try schema.getRootpage(allocator, &file, page_size, table_name);
// Read and print all rows
try schema.readTableRows(allocator, &file, page_size, rootpage, column_idx, stdout);
}
} else {
var tokens = std.mem.tokenizeScalar(u8, args[2], ' ');
var last_token: []const u8 = "";
while (tokens.next()) |token| {
last_token = token;
}
const rootpage = try schema.getRootpage(allocator, &file, page_size, last_token);
const row_count = try schema.countRows(allocator, &file, page_size, rootpage);
try stdout.print("{}\n", .{row_count});
}
try stdout.flush();
}
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