module build

import docker
import encoding.base64
import time
import os
import strings
import util
import models { BuildConfig, Target }

const (
	container_build_dir = '/build'
	build_image_repo    = 'vieter-build'
	// Contents of PATH variable in build containers
	path_dirs           = ['/sbin', '/bin', '/usr/sbin', '/usr/bin', '/usr/local/sbin',
		'/usr/local/bin', '/usr/bin/site_perl', '/usr/bin/vendor_perl', '/usr/bin/core_perl']
)

// create_build_image creates a builder image given some base image which can
// then be used to build & package Arch images. It mostly just updates the
// system, install some necessary packages & creates a non-root user to run
// makepkg with. The base image should be some Linux distribution that uses
// Pacman as its package manager.
pub fn create_build_image(base_image string) !string {
	mut dd := docker.new_conn()!

	defer {
		dd.close() or {}
	}

	commands := [
		// Update repos & install required packages
		'pacman -Syu --needed --noconfirm base-devel git'
		// Add a non-root user to run makepkg
		'groupadd -g 1000 builder',
		'useradd -mg builder builder'
		// Make sure they can use sudo without a password
		"echo 'builder ALL=(ALL) NOPASSWD: ALL' >> /etc/sudoers"
		// Create the directory for the builds & make it writeable for the
		// build user
		'mkdir /build',
		'chown -R builder:builder /build',
	]
	cmds_str := base64.encode_str(commands.join('\n'))

	c := docker.NewContainer{
		image: base_image
		env: ['BUILD_SCRIPT=${cmds_str}']
		entrypoint: ['/bin/sh', '-c']
		cmd: ['echo \$BUILD_SCRIPT | base64 -d | /bin/sh -e']
	}

	// This check is needed so the user can pass "archlinux" without passing a
	// tag & make it still work
	image_parts := base_image.split_nth(':', 2)
	image_name := image_parts[0]
	image_tag := if image_parts.len > 1 { image_parts[1] } else { 'latest' }

	// We pull the provided image
	dd.image_pull(image_name, image_tag)!

	id := dd.container_create(c)!.id
	// id := docker.create_container(c)!
	dd.container_start(id)!

	// This loop waits until the container has stopped, so we can remove it after
	for {
		data := dd.container_inspect(id)!

		if !data.state.running {
			break
		}

		time.sleep(1 * time.second)
	}

	// Finally, we create the image from the container
	// As the tag, we use the epoch value
	// TODO also add the base image's name into the image name to prevent
	// conflicts.
	tag := time.sys_mono_now().str()
	image := dd.image_from_container(id, 'vieter-build', tag)!
	dd.container_remove(id)!

	return image.id
}

pub struct BuildResult {
pub:
	start_time time.Time
	end_time   time.Time
	exit_code  int
	logs       string
}

// build_target builds the given target. Internally it calls `build_config`.
pub fn build_target(address string, api_key string, base_image_id string, target &Target, force bool, timeout int) !BuildResult {
	config := target.as_build_config(base_image_id, force, timeout)

	return build_config(address, api_key, config)
}

// build_config builds, packages & publishes a given Arch package based on the
// provided target. The base image ID should be of an image previously created
// by create_build_image. It returns the logs of the container.
pub fn build_config(address string, api_key string, config BuildConfig) !BuildResult {
	mut dd := docker.new_conn()!

	defer {
		dd.close() or {}
	}

	build_arch := os.uname().machine
	build_script := create_build_script(address, config, build_arch)

	// We convert the build script into a base64 string, which then gets passed
	// to the container as an env var
	base64_script := base64.encode_str(build_script)

	c := docker.NewContainer{
		image: '${config.base_image}'
		env: [
			'BUILD_SCRIPT=${base64_script}',
			'API_KEY=${api_key}',
			// `archlinux:base-devel` does not correctly set the path variable,
			// causing certain builds to fail. This fixes it.
			'PATH=${build.path_dirs.join(':')}',
		]
		entrypoint: ['/bin/sh', '-c']
		cmd: ['echo \$BUILD_SCRIPT | base64 -d | /bin/bash -e']
		work_dir: '/build'
		user: '0:0'
	}

	id := dd.container_create(c)!.id
	dd.container_start(id)!

	mut data := dd.container_inspect(id)!
	start_time := time.now()

	// This loop waits until the container has stopped, so we can remove it after
	for data.state.running {
		if time.now() - start_time > config.timeout * time.second {
			dd.container_kill(id)!
			dd.container_remove(id)!

			return error('Build killed due to timeout (${config.timeout}s)')
		}

		time.sleep(1 * time.second)

		data = dd.container_inspect(id)!
	}

	mut logs_stream := dd.container_get_logs(id)!

	// Read in the entire stream
	mut logs_builder := strings.new_builder(10 * 1024)
	util.reader_to_writer(mut logs_stream, mut logs_builder)!

	dd.container_remove(id)!

	return BuildResult{
		start_time: data.state.start_time
		end_time: data.state.end_time
		exit_code: data.state.exit_code
		logs: logs_builder.str()
	}
}