const std = @import("std");

pub fn main() !void {
    const reader = std.io.getStdIn().reader();
    const writer = std.io.getStdOut().writer();
    const rand = std.crypto.random;

    try writer.print("Welcome to my number guessing game! \n\n", .{});

    try writer.print("Enter an upper limit: \n", .{});
    const upperLimit: i64 = try oneIntInput(writer, reader);
    try writer.print("The number you need to find is between 0 and {d}! \n\n", .{upperLimit});

    const targetNumber: i64 = rand.intRangeLessThan(i64, 0, upperLimit);
    
    try writer.print("Target: {d} \n", .{targetNumber});
    
    var counter: i64 = 0; 
    while(true) {
        counter += 1;
        try writer.print("\nEnter your guess: \n", .{});
        const userGuess = try oneIntInput(writer, reader);
        
        if (targetNumber == userGuess) {
            try writer.print("Your guess {d} is correct! \n", .{userGuess});
            try writer.print("It took you {d} tries. \n", .{counter});
            return;
        }
        if (targetNumber > userGuess) {
            try writer.print("Your guess '{d}' is smaller then the target number, try again! \n", .{userGuess});
        }
        else {
            try writer.print("Your guess '{d}' is bigger then the target number, try again! \n", .{userGuess});
        }
    }
}

pub fn oneIntInput(writer: anytype, reader: anytype) !i64 {
    var buffer: [256]u8 = undefined;

    while (true) {
        try writer.print("> ", .{});
        const amountInputBytes = try reader.read(&buffer);
        const input_slice: []u8 = buffer[0..(amountInputBytes - 1)];

        const result = std.fmt.parseInt(i64, input_slice, 10) catch |err| {
            switch (err) {
                error.InvalidCharacter => {
                    try writer.print("Error: '{s}' contains invalid character, try again! \n", .{input_slice});
                },
                error.Overflow => {
                    try writer.print("Error: '{s}' ist too big for an i64, try again! \n", .{input_slice});
                },
            }
            try writer.print("\n", .{});
            continue;
        };
        return result;
    }
}