// Package chain keeps the controller's chain on the bus alone (novox/hq ADR 0408, design 47): module, commit, build,
// published artifact or package, rollout and assignment are one chain, a bucket each of the bus's key-value store,
// each the only source of its kind, written by the controller that holds the lease by compare-and-set.
//
// **No key is removed.** A Backend has no delete and no purge (ADR 0408 §4): an assignment of a module taken off its
// node is kept, saying so. **A value is never cut** (§6): one over the largest the bus holds is refused, and the key
// stays as it was. **Each key keeps its earlier values** (§5), read back with History.
package chain

import (
	"encoding/json"
	"time"
)

// Ref names a build and the commit it was made from: one end of a change.
type Ref struct {
	Build  string `json:"build,omitempty"`
	Commit string `json:"commit,omitempty"`
}

// Package is a release a build published to the package registry.
type Package struct {
	Name    string `json:"name"`
	Version string `json:"version"`
}

// Published is what a build published: an artifact by its digest, or a package release by name and version.
type Published struct {
	Artifact string   `json:"artifact,omitempty"`
	Package  *Package `json:"package,omitempty"`
}

// Artifact is one thing a build made.
type Artifact struct {
	Name      string `json:"name"`
	Kind      string `json:"kind"`
	Reference string `json:"reference"`
}

// ReadRepository is a repository a build read source from besides the module's own.
type ReadRepository struct {
	Repository string   `json:"repository"`
	Ref        string   `json:"ref,omitempty"`
	Paths      []string `json:"paths,omitempty"`
	Own        bool     `json:"own,omitempty"`
}

// Source is the build source a build read in one repository.
type Source struct {
	Repository string   `json:"repository,omitempty"`
	Ref        string   `json:"ref,omitempty"`
	Paths      []string `json:"paths"`
}

// The states of a build record. A record in state asked is a request that no outcome has answered (issue 1091); one
// without a state is an outcome.
const BuildAsked = "asked"

// Build is one attempt, whichever way it went, kept under its id. It names its module, its repository and commit, its
// reuse key (novox/hq ADR 0350) and what it published (ADR 0408 §1).
type Build struct {
	ID                string           `json:"id"`
	State             string           `json:"state,omitempty"`
	Repository        string           `json:"repository"`
	Ref               string           `json:"ref,omitempty"`
	Module            string           `json:"module,omitempty"`
	Commit            string           `json:"commit,omitempty"`
	On                string           `json:"on,omitempty"`
	Path              string           `json:"path,omitempty"`
	Manifest          json.RawMessage  `json:"manifest,omitempty"`
	Against           []string         `json:"against,omitempty"`
	Mirrored          []string         `json:"mirrored,omitempty"`
	Read              []ReadRepository `json:"read,omitempty"`
	Sources           []Source         `json:"sources,omitempty"`
	SourceFingerprint string           `json:"source-fingerprint,omitempty"`
	Failed            string           `json:"failed,omitempty"`
	Made              []Artifact       `json:"made,omitempty"`
	Asked             time.Time        `json:"asked,omitzero"`
	At                time.Time        `json:"at,omitzero"`
	ReuseKey          string           `json:"reuse-key,omitempty"`
	Published         *Published       `json:"published,omitempty"`
}

// Commit is one repository's commit a rollout carries.
type Commit struct {
	Repository string    `json:"repository"`
	Branch     string    `json:"branch,omitempty"`
	Commit     string    `json:"commit"`
	Merged     time.Time `json:"merged,omitzero"`
}

// Change is one assignment a rollout changed: the build and commit it ran before and the ones it runs after.
type Change struct {
	Node   string `json:"node"`
	Module string `json:"module"`
	Before Ref    `json:"before"`
	After  Ref    `json:"after"`
}

// Step is one tier sent to one machine.
type Step struct {
	Tier     int        `json:"tier"`
	Node     string     `json:"node"`
	Sent     *time.Time `json:"sent,omitempty"`
	Reported *time.Time `json:"reported,omitempty"`
}

// Links are the fields a rollout gains on the chain: the builds it carried, the machine steps it has taken and the
// assignments it changed, each with the build before and after. The controller's plan embeds them, so the plan's own
// fields and these are one value (ADR 0408 §1).
type Links struct {
	Builds  []string `json:"builds,omitempty"`
	Steps   []Step   `json:"steps,omitempty"`
	Changed []Change `json:"changed,omitempty"`
}

// Rollout is the controller's record of one batch's delivery, kept under the batch's id: the commit it fixed per
// repository, its tiers, the builds it carried and the assignments it changed (ADR 0408 §1). The controller's plan
// carries more (its modules, its times, its backups) beside these, under the same key.
type Rollout struct {
	ID      string     `json:"id"`
	State   string     `json:"state,omitempty"`
	Commits []Commit   `json:"commits,omitempty"`
	Tiers   [][]string `json:"tiers,omitempty"`
	Links
}

// Assignment is one module on one node, kept under `<node>.<module>`. The first five fields are the ones its readers
// have always read, with the names they have always had (novox/hq ADR 0408 §3); the rest name the chain: the build, the
// artifact (by digest) or the package it runs, its commit, the rollout that put it there and since when.
type Assignment struct {
	Node         string          `json:"node"`
	Module       string          `json:"module"`
	Assigned     time.Time       `json:"assigned,omitzero"`
	RequiredBy   string          `json:"required-by,omitempty"`
	Provisioning json.RawMessage `json:"provisioning,omitempty"`

	Build    string    `json:"build,omitempty"`
	Artifact string    `json:"artifact,omitempty"`
	Package  *Package  `json:"package,omitempty"`
	Commit   string    `json:"commit,omitempty"`
	Rollout  string    `json:"rollout,omitempty"`
	Since    time.Time `json:"since,omitzero"`
}

// Key is an assignment's key.
func (a Assignment) Key() string { return a.Node + "." + a.Module }