package golang

import (
	"fmt"
	"strings"

	"github.com/apex/log"
	"github.com/goreleaser/goreleaser/pkg/config"
)

type target struct {
	os, arch, arm, mips string
}

func (t target) String() string {
	if t.arm != "" {
		return fmt.Sprintf("%s_%s_%s", t.os, t.arch, t.arm)
	}
	if t.mips != "" {
		return fmt.Sprintf("%s_%s_%s", t.os, t.arch, t.mips)
	}
	return fmt.Sprintf("%s_%s", t.os, t.arch)
}

func matrix(build config.Build) (result []string) {
	// nolint:prealloc
	var targets []target
	for _, target := range allBuildTargets(build) {
		if !valid(target) {
			log.WithField("target", target).
				Debug("skipped invalid build")
			continue
		}
		if ignored(build, target) {
			log.WithField("target", target).
				Debug("skipped ignored build")
			continue
		}
		targets = append(targets, target)
	}
	for _, target := range targets {
		result = append(result, target.String())
	}
	return
}

func allBuildTargets(build config.Build) (targets []target) {
	for _, goos := range build.Goos {
		for _, goarch := range build.Goarch {
			if goarch == "arm" {
				for _, goarm := range build.Goarm {
					targets = append(targets, target{
						os:   goos,
						arch: goarch,
						arm:  goarm,
					})
				}
				continue
			}
			if strings.HasPrefix(goarch, "mips") {
				for _, gomips := range build.Gomips {
					targets = append(targets, target{
						os:   goos,
						arch: goarch,
						mips: gomips,
					})
				}
				continue
			}
			targets = append(targets, target{
				os:   goos,
				arch: goarch,
			})
		}
	}
	return
}

// TODO: this could be improved by using a map
// https://github.com/goreleaser/goreleaser/pull/522#discussion_r164245014
func ignored(build config.Build, target target) bool {
	for _, ig := range build.Ignore {
		if ig.Goos != "" && ig.Goos != target.os {
			continue
		}
		if ig.Goarch != "" && ig.Goarch != target.arch {
			continue
		}
		if ig.Goarm != "" && ig.Goarm != target.arm {
			continue
		}
		if ig.Gomips != "" && ig.Gomips != target.mips {
			continue
		}
		return true
	}
	return false
}

func valid(target target) bool {
	var s = target.os + target.arch
	for _, a := range validTargets {
		if a == s {
			return true
		}
	}
	return false
}

// list from https://golang.org/doc/install/source#environment
// nolint: gochecknoglobals
var validTargets = []string{
	"aixppc64",
	"android386",
	"androidamd64",
	"androidarm",
	"androidarm64",
	// "darwin386", - deprecated on latest go 1.15+
	"darwinamd64",
	// "darwinarm", - requires admin rights and other ios stuff
	// "darwinarm64", - requires admin rights and other ios stuff
	"dragonflyamd64",
	"freebsd386",
	"freebsdamd64",
	"freebsdarm",
	"freebsdarm64", // not on the official list for some reason, yet its supported on go 1.14+
	"illumosamd64",
	"jswasm",
	"linux386",
	"linuxamd64",
	"linuxarm",
	"linuxarm64",
	"linuxppc64",
	"linuxppc64le",
	"linuxmips",
	"linuxmipsle",
	"linuxmips64",
	"linuxmips64le",
	"linuxs390x",
	"netbsd386",
	"netbsdamd64",
	"netbsdarm",
	"openbsd386",
	"openbsdamd64",
	"openbsdarm",
	"openbsdarm64",
	"plan9386",
	"plan9amd64",
	"plan9arm",
	"solarisamd64",
	"windows386",
	"windowsamd64",
}