// Package build is the builder's logic (novox/hq ADR 0453 clause 4, ADR 0478), apart from the bus: what a manifest asks
// to be built and where, the claim of a build key, the choice of build nodes, the build modules' long steps and the run of
// one build. The bus is reached through the small interfaces here, so each part is tested with fakes.
package build

import (
	"fmt"
	"sort"
	"strings"

	"git.novox.be/novox/mesh-sdk/go/catalogue"
	"git.novox.be/novox/mesh-sdk/go/delivery"
	"git.novox.be/novox/mesh-sdk/go/delivery/buildrun"
)

// ImageBuildModule is the build module that builds an image artifact (novox/hq ADR 0487): buildah, rootless, on the nodes that
// run it. It has no toolchain language; the builder finds its nodes from the node-engine's have.
const ImageBuildModule = "mesh-build-image"

// NoImageBuilderPrefix opens the error of a build key failed because no node runs ImageBuildModule (ADR 0487 clause 5): such a
// key is not built again as a new revision, only when a node reports the module (ClaimOptions.ImageBuilder) or the fingerprint
// changes.
const NoImageBuilderPrefix = "no image builder:"

// Task is one artifact to build: its name and kind in the manifest, the build module that builds it and the language
// of the toolchain it is built with.
type Task struct {
	Artifact string
	Kind     string
	Module   string
	Language string
	// From is, for an upstream artifact, the reference its manifest pins, which the image build module copies (ADR 0498
	// clause 4).
	From string
}

// Plan is what a manifest asks the builder to build, by artifact name.
type Plan struct{ Tasks []Task }

// Modules are the build modules the plan calls, sorted.
func (p Plan) Modules() []string {
	seen := map[string]bool{}
	var out []string
	for _, t := range p.Tasks {
		if !seen[t.Module] {
			seen[t.Module] = true
			out = append(out, t.Module)
		}
	}
	sort.Strings(out)
	return out
}

// NeedsToolchain is whether any task the build module builds is built with a toolchain: a bundle is, an archive is not
// (the indexer gives an archive no language, so a fingerprint names no toolchain for it; ADR 0478 clause 1).
func (p Plan) NeedsToolchain(module string) bool {
	for _, t := range p.Tasks {
		if t.Module == module && t.Kind != catalogue.ArtifactArchive && t.Kind != catalogue.ArtifactImage && t.Kind != catalogue.ArtifactUpstream {
			return true
		}
	}
	return false
}

// Refused is the error of a plan the builder does not build: an artifact of a kind (or of a language) no build module
// builds. It opens delivery.RefusedKind, so its key is not built again until the fingerprint changes.
type Refused struct{ Artifact, What string }

func (r *Refused) Error() string {
	return fmt.Sprintf("%s%s (artifact %s): no build module builds it; the builder builds Go and TypeScript bundles, archives, images, upstream copies and TypeScript packages", delivery.RefusedKind, r.What, r.Artifact)
}

// NotPinned is the error of a plan with an upstream artifact whose reference names no digest (ADR 0498 clause 4): it opens
// delivery.NotPinned, so its key is not built again until the fingerprint changes.
type NotPinned struct{ Artifact, From string }

func (n *NotPinned) Error() string {
	return fmt.Sprintf("%s%s: %q names no digest (@sha256:), so what would be copied is whatever its tag means today", delivery.NotPinned, n.Artifact, n.From)
}

// PlanOf is the plan of a manifest (ADR 0478 clauses 1 and 2, ADR 0498 clauses 4 and 5): a Go bundle and an archive are
// built by the Go build module, an image by the image build module (ADR 0487), which also copies an upstream image pinned
// by its digest, and a TypeScript bundle or package by the Node one, each in the order of the artifacts' names. A manifest
// with an upstream artifact pinned by no digest, or a bundle or a package of another language, or a kind no build module
// builds, is refused as a whole, naming the first such artifact by name. A manifest with no artifact has an empty plan.
func PlanOf(m catalogue.Manifest) (Plan, error) {
	if m.Build == nil {
		return Plan{}, nil
	}
	artifacts := append([]catalogue.Artifact(nil), m.Build.Artifacts...)
	sort.Slice(artifacts, func(i, j int) bool { return artifacts[i].Name < artifacts[j].Name })
	var p Plan
	for _, a := range artifacts {
		switch {
		case a.Kind == catalogue.ArtifactArchive:
			p.Tasks = append(p.Tasks, Task{Artifact: a.Name, Kind: a.Kind, Module: buildrun.GoBuildModule, Language: "go"})
		case a.Kind == catalogue.ArtifactBundle && a.Language == "go":
			p.Tasks = append(p.Tasks, Task{Artifact: a.Name, Kind: a.Kind, Module: buildrun.GoBuildModule, Language: "go"})
		case a.Kind == catalogue.ArtifactBundle && a.Language == "typescript":
			p.Tasks = append(p.Tasks, Task{Artifact: a.Name, Kind: a.Kind, Module: buildrun.NodeBuildModule, Language: "typescript"})
		case a.Kind == catalogue.ArtifactImage:
			p.Tasks = append(p.Tasks, Task{Artifact: a.Name, Kind: a.Kind, Module: ImageBuildModule})
		case a.Kind == catalogue.ArtifactUpstream && !strings.Contains(a.From, "@sha256:"):
			return Plan{}, &NotPinned{Artifact: a.Name, From: a.From}
		case a.Kind == catalogue.ArtifactUpstream:
			p.Tasks = append(p.Tasks, Task{Artifact: a.Name, Kind: a.Kind, Module: ImageBuildModule, From: a.From})
		case a.Kind == catalogue.ArtifactPackage && a.Language == "typescript":
			p.Tasks = append(p.Tasks, Task{Artifact: a.Name, Kind: a.Kind, Module: buildrun.NodeBuildModule, Language: "typescript"})
		case a.Kind == catalogue.ArtifactBundle:
			return Plan{}, &Refused{Artifact: a.Name, What: fmt.Sprintf("bundle of language %q", a.Language)}
		case a.Kind == catalogue.ArtifactPackage:
			return Plan{}, &Refused{Artifact: a.Name, What: fmt.Sprintf("package of language %q", a.Language)}
		default:
			return Plan{}, &Refused{Artifact: a.Name, What: a.Kind}
		}
	}
	return p, nil
}