const std = @import("std");
const builtin = @import("builtin");
const testing = std.testing;
const expectEqual = testing.expectEqual;
const expect = testing.expect;
const maxInt = std.math.maxInt;

comptime {
    // This is a workaround for https://github.com/ziglang/zig/issues/8218
    // which is only necessary on macOS.
    //
    // Once that issue is fixed, we can undo the changes in
    // 177cf12e0555147faa4d436e52fc15175c2c4ff0 and go back to passing
    // -fcompiler-rt in link.rs instead of doing this. Note that this
    // workaround is present in many host.zig files, so make sure to undo
    // it everywhere!
    if (builtin.os.tag == .macos) {
        _ = @import("compiler_rt");
    }
}

const mem = std.mem;
const Allocator = mem.Allocator;

// NOTE the LLVM backend expects this signature
// extern fn roc__mainForHost_1_exposed(i64, *i64) void;
extern fn roc__mainForHost_1_exposed(i64) i64;

const Align = 2 * @alignOf(usize);
extern fn malloc(size: usize) callconv(.C) ?*align(Align) anyopaque;
extern fn realloc(c_ptr: [*]align(Align) u8, size: usize) callconv(.C) ?*anyopaque;
extern fn free(c_ptr: [*]align(Align) u8) callconv(.C) void;
extern fn memcpy(dst: [*]u8, src: [*]u8, size: usize) callconv(.C) void;
extern fn memset(dst: [*]u8, value: i32, size: usize) callconv(.C) void;

const DEBUG: bool = false;

export fn roc_alloc(size: usize, alignment: u32) callconv(.C) ?*anyopaque {
    if (DEBUG) {
        var ptr = malloc(size);
        const stdout = std.io.getStdOut().writer();
        stdout.print("alloc:   {d} (alignment {d}, size {d})\n", .{ ptr, alignment, size }) catch unreachable;
        return ptr;
    } else {
        return malloc(size);
    }
}

export fn roc_realloc(c_ptr: *anyopaque, new_size: usize, old_size: usize, alignment: u32) callconv(.C) ?*anyopaque {
    if (DEBUG) {
        const stdout = std.io.getStdOut().writer();
        stdout.print("realloc: {d} (alignment {d}, old_size {d})\n", .{ c_ptr, alignment, old_size }) catch unreachable;
    }

    return realloc(@alignCast(Align, @ptrCast([*]u8, c_ptr)), new_size);
}

export fn roc_dealloc(c_ptr: *anyopaque, alignment: u32) callconv(.C) void {
    if (DEBUG) {
        const stdout = std.io.getStdOut().writer();
        stdout.print("dealloc: {d} (alignment {d})\n", .{ c_ptr, alignment }) catch unreachable;
    }

    free(@alignCast(Align, @ptrCast([*]u8, c_ptr)));
}

export fn roc_panic(c_ptr: *anyopaque, tag_id: u32) callconv(.C) void {
    _ = tag_id;

    const stderr = std.io.getStdErr().writer();
    const msg = @ptrCast([*:0]const u8, c_ptr);
    stderr.print("Application crashed with message\n\n    {s}\n\nShutting down\n", .{msg}) catch unreachable;
    std.process.exit(0);
}

export fn roc_memcpy(dst: [*]u8, src: [*]u8, size: usize) callconv(.C) void {
    return memcpy(dst, src, size);
}

export fn roc_memset(dst: [*]u8, value: i32, size: usize) callconv(.C) void {
    return memset(dst, value, size);
}

extern fn kill(pid: c_int, sig: c_int) c_int;
extern fn shm_open(name: *const i8, oflag: c_int, mode: c_uint) c_int;
extern fn mmap(addr: ?*anyopaque, length: c_uint, prot: c_int, flags: c_int, fd: c_int, offset: c_uint) *anyopaque;
extern fn getppid() c_int;

fn roc_getppid() callconv(.C) c_int {
    return getppid();
}

fn roc_getppid_windows_stub() callconv(.C) c_int {
    return 0;
}

fn roc_shm_open(name: *const i8, oflag: c_int, mode: c_uint) callconv(.C) c_int {
    return shm_open(name, oflag, mode);
}
fn roc_mmap(addr: ?*anyopaque, length: c_uint, prot: c_int, flags: c_int, fd: c_int, offset: c_uint) callconv(.C) *anyopaque {
    return mmap(addr, length, prot, flags, fd, offset);
}

comptime {
    if (builtin.os.tag == .macos or builtin.os.tag == .linux) {
        @export(roc_getppid, .{ .name = "roc_getppid", .linkage = .Strong });
        @export(roc_mmap, .{ .name = "roc_mmap", .linkage = .Strong });
        @export(roc_shm_open, .{ .name = "roc_shm_open", .linkage = .Strong });
    }

    if (builtin.os.tag == .windows) {
        @export(roc_getppid_windows_stub, .{ .name = "roc_getppid", .linkage = .Strong });
    }
}

pub export fn main() u8 {
    const stdout = std.io.getStdOut().writer();

    var timer = std.time.Timer.start() catch unreachable;

    const result = roc__mainForHost_1_exposed(10);

    const nanos = timer.read();
    const seconds = (@intToFloat(f64, nanos) / 1_000_000_000.0);

    stdout.print("{d}\n", .{result}) catch unreachable;

    const stderr = std.io.getStdErr().writer();
    stderr.print("runtime: {d:.3}ms\n", .{seconds * 1000}) catch unreachable;

    return 0;
}

fn to_seconds(tms: std.os.timespec) f64 {
    return @intToFloat(f64, tms.tv_sec) + (@intToFloat(f64, tms.tv_nsec) / 1_000_000_000.0);
}