package delivery

import (
	"encoding/json"
	"fmt"
	"reflect"
	"strings"
)

// The builder's keys (novox/hq ADR 0429 clauses 5 and 16, ADR 0437 clause 5, ADR 0405 clauses 2 and 7, ADR 0453
// clause 4): a build is `<module>.<fingerprint key part>` in the builder's bucket, one key per fingerprint, since equal
// fingerprints are equal content and the same source is never built twice. They are written only by the builder part
// from R4c and read by the checker, the assigner and the view, and from R4e by the controller. They are not the
// controller's build records (buildrecord.go: BuildsBucket, BuildKey), which stay as they are.
//
// **The rules its writer keeps.** A builder claims a fingerprint that has no build key by creating it queued or
// building, a create that fails when the key exists, and moves it by compare-and-set; a builder reclaims only a build
// whose `by` is offline in presence. A failed key is built again as a new revision of the same key (ADR 0429 clause
// 18). Only the builder's credential writes the bucket (clause 5); every other part reads it.
const (
	// BuilderModule is the module of the builder part.
	BuilderModule = "mesh-delivery-builder"
	// BuilderBuildsBucket is the builder's bucket of builds: `<owner module>_<name>`.
	BuilderBuildsBucket = BuilderModule + "_builds"
	// BuilderBuildsHistory is the revisions the bucket keeps per key.
	BuilderBuildsHistory = 5
)

// The states of a build.
const (
	BuildQueued   = "queued"
	BuildBuilding = "building"
	BuildDone     = "done"
	BuildFailed   = "failed"
)

// BuilderBuildKey is the key, in BuilderBuildsBucket, of a module's build at a fingerprint: `<module>.<hex>`, the hex
// being the fingerprint's key part (FingerprintKeyPart), since a bus key may not hold ':'. A module holding a dot or a
// character a key refuses, and a fingerprint not of the new form, are refused, naming them.
func BuilderBuildKey(module, fingerprint string) (string, error) {
	if err := checkName("module", module); err != nil {
		return "", err
	}
	part, err := FingerprintKeyPart(fingerprint)
	if err != nil {
		return "", err
	}
	return module + "." + part, nil
}

// ParseBuilderBuildKey is the inverse of BuilderBuildKey: the module and the fingerprint (`src2:` and the hex).
func ParseBuilderBuildKey(key string) (module, fingerprint string, err error) {
	module, part, ok := strings.Cut(key, ".")
	if !ok {
		return "", "", fmt.Errorf("delivery: %q is not a builder build key, <module>.<fingerprint hex>", key)
	}
	if err := checkName("module", module); err != nil {
		return "", "", fmt.Errorf("delivery: %q is not a builder build key: %w", key, err)
	}
	if fingerprint, err = ParseFingerprintKeyPart(part); err != nil {
		return "", "", fmt.Errorf("delivery: %q is not a builder build key: %w", key, err)
	}
	return module, fingerprint, nil
}

// BuiltArtifact is one artifact of a done build: its name in the manifest, its kind, its content digest and, for an
// image, the reference it was pushed to.
type BuiltArtifact struct {
	Name      string `json:"name"`
	Kind      string `json:"kind,omitempty"`
	Digest    string `json:"digest"`
	Reference string `json:"reference,omitempty"`
}

// ToolchainUsed is what a build used for one language (ADR 0405 clauses 2 and 7): the installed toolchain's version and
// the build module's recipe version.
type ToolchainUsed struct {
	Version string `json:"version"`
	Recipe  string `json:"recipe"`
}

// BuilderBuild is the value of a builder build key: its State (queued, building, done or failed), By the builder
// instance that holds it, Step what it is doing or did last, Manifest the digest of the module's manifest (the key of
// the indexer's manifests bucket), Artifacts when done, Toolchains by language when it built or is building (a done
// build names them, so two builders that differ are seen: ADR 0405 clause 2), and Error when failed.
type BuilderBuild struct {
	V          int                      `json:"v"`
	State      string                   `json:"state"`
	By         string                   `json:"by,omitempty"`
	Step       string                   `json:"step,omitempty"`
	Manifest   string                   `json:"manifest,omitempty"`
	Artifacts  []BuiltArtifact          `json:"artifacts,omitempty"`
	Toolchains map[string]ToolchainUsed `json:"toolchains,omitempty"`
	Error      string                   `json:"error,omitempty"`
}

func (b BuilderBuild) check() error {
	switch b.State {
	case BuildQueued, BuildBuilding, BuildDone, BuildFailed:
	default:
		return fmt.Errorf("delivery: the build state %q is not queued, building, done or failed", b.State)
	}
	if b.Manifest != "" {
		if _, err := ManifestsKey(b.Manifest); err != nil {
			return err
		}
	}
	for language, t := range b.Toolchains {
		if t.Version == "" {
			return fmt.Errorf("delivery: the toolchain of %q has no version", language)
		}
		if t.Recipe == "" {
			return fmt.Errorf("delivery: the toolchain of %q has no recipe version", language)
		}
	}
	for i, a := range b.Artifacts {
		if a.Name == "" {
			return fmt.Errorf("delivery: artifact %d of the build has no name", i)
		}
		if a.Digest == "" {
			return fmt.Errorf("delivery: the artifact %q of the build has no digest", a.Name)
		}
	}
	switch b.State {
	case BuildQueued, BuildBuilding:
		if len(b.Artifacts) > 0 || b.Error != "" {
			return fmt.Errorf("delivery: a %s build carries no artifact and no error", b.State)
		}
	case BuildDone:
		if len(b.Artifacts) == 0 {
			return fmt.Errorf("delivery: a done build names no artifact")
		}
		if b.Manifest == "" {
			return fmt.Errorf("delivery: a done build names no manifest digest")
		}
		if b.Error != "" {
			return fmt.Errorf("delivery: a done build carries an error")
		}
	case BuildFailed:
		if b.Error == "" {
			return fmt.Errorf("delivery: a failed build says no error")
		}
	}
	return nil
}

// EncodeBuilderBuild is b as JSON at Version; it refuses a build its state does not allow (done without artifacts or a
// manifest digest, failed without an error, an artifact without a name or digest, a toolchain without a version or a
// recipe version).
func EncodeBuilderBuild(b BuilderBuild) ([]byte, error) {
	if err := b.check(); err != nil {
		return nil, err
	}
	b.V = Version
	return json.Marshal(b)
}

// DecodeBuilderBuild reads a builder build value; it refuses an unknown version (ErrUnknownVersion) and what
// EncodeBuilderBuild refuses.
func DecodeBuilderBuild(data []byte) (BuilderBuild, error) {
	var b BuilderBuild
	if err := decode(data, &b); err != nil {
		return BuilderBuild{}, err
	}
	if err := b.check(); err != nil {
		return BuilderBuild{}, err
	}
	return b, nil
}

// SameBuilderBuild says whether two builds are the same value, so the builder writes only when they differ.
func SameBuilderBuild(a, b BuilderBuild) bool { return reflect.DeepEqual(a, b) }