package common

import "core:bytes"
import "core:fmt"
import "core:log"
import "core:mem"
import "core:os"
import "core:path/filepath"
import "core:path/slashpath"
import "core:strings"

foreign import libc "system:c"

when ODIN_OS == .Windows {
	delimiter :: ";"
} else {
	delimiter :: ":"
}

//TODO(daniel): This is temporary and should not be needed after os2
File_Mode_User_Executable :: os.File_Mode(1 << 8)

lookup_in_path :: proc(name: string) -> (string, bool) {
	path := os.get_env("PATH", context.temp_allocator)

	for directory in strings.split_iterator(&path, delimiter) {
		when ODIN_OS == .Windows {
			possibility := filepath.join(
				elems = {directory, fmt.tprintf("%v.exe", name)},
				allocator = context.temp_allocator,
			)
			if os.exists(possibility) {
				return possibility, true
			}
		} else {
			possibility := filepath.join(
				elems = {directory, name},
				allocator = context.temp_allocator,
			)
			possibility = resolve_home_dir(possibility, context.temp_allocator)
			if os.exists(possibility) {
				if info, err := os.stat(possibility, context.temp_allocator);
				   err == os.ERROR_NONE &&
				   (File_Mode_User_Executable & info.mode) != 0 {
					return possibility, true
				}
			}
		}
	}

	return "", false
}

resolve_home_dir :: proc(
	path: string,
	allocator := context.allocator,
) -> (
	resolved: string,
	allocated: bool,
) #optional_ok {
	when ODIN_OS == .Windows {
		return path, false
	} else {
		if !strings.has_prefix(path, "~") {
			return path, false
		}

		home := os.get_env("HOME", context.temp_allocator)
		if home == "" {
			log.error(
				"could not find $HOME in the environment to be able to resolve ~ in collection paths",
			)
			return path, false
		}

		return filepath.join({home, path[1:]}, allocator), true
	}
}

when ODIN_OS == .Darwin || ODIN_OS == .Linux || ODIN_OS == .NetBSD {
	FILE :: struct {}

	run_executable :: proc(
		command: string,
		stdout: ^[]byte,
	) -> (
		u32,
		bool,
		[]byte,
	) {
		fp := popen(
			strings.clone_to_cstring(command, context.temp_allocator),
			"r",
		)
		if fp == nil {
			return 0, false, stdout[0:]
		}
		defer pclose(fp)

		read_buffer: [50]byte
		index: int

		for fgets(&read_buffer[0], size_of(read_buffer), fp) != nil {
			read := bytes.index_byte(read_buffer[:], 0)
			defer index += cast(int)read

			if read > 0 && index + cast(int)read <= len(stdout) {
				mem.copy(&stdout[index], &read_buffer[0], cast(int)read)
			}
		}


		return 0, true, stdout[0:index]
	}

	foreign libc 
	{
		popen :: proc(command: cstring, type: cstring) -> ^FILE ---
		pclose :: proc(stream: ^FILE) -> i32 ---
		fgets :: proc "cdecl" (s: [^]byte, n: i32, stream: ^FILE) -> [^]u8 ---
		fgetc :: proc "cdecl" (stream: ^FILE) -> i32 ---
	}
}

get_executable_path :: proc(allocator := context.temp_allocator) -> string {
	exe_path, ok := filepath.abs(
		slashpath.dir(os.args[0], context.temp_allocator),
		context.temp_allocator,
	)
	if !ok {
		log.error("Failed to resolve executable path")
		return ""
	}
	return exe_path
}