package builds

import (
	"encoding/json"
	"fmt"
	"sort"
	"time"

	"git.novox.be/novox/mesh-delivery/sdk/trunk"
	"git.novox.be/novox/mesh-sdk/go/keys"
)

// The builder's log (clause 1; the lead and the operator, 2026-10-29): the builder's own module log (ADR 0297) `build-log`,
// kept 30 days (max-age-days), one entry under the key `<module>` when a build of a fingerprint starts and one when it
// ends, so the newest entry of a key is the module's newest start or end. The builder's tools read it through the
// runtime's log verbs; another module reads it by naming BuildLogRead in its manifest's `reads`: a bundle through the
// runtime (stdio.Log(BuildLogRead)), a process on its own credential (process.Conn.ReadLog), each by newest per key,
// from a time, or following new entries. The catalogue module asks the builder's tool BuildsSinceTool instead.
const (
	BuilderLog        = "build-log"
	BuildLogRead      = BuilderModule + "." + BuilderLog
	BuildStartedEvent = "build.started"
	BuildEndedEvent   = "build.ended"
	// BuildSaidEvent is a build's narration between its start and its end (design 51: a build narrates its publish,
	// asked, waiting on a seat, stored, refused, at least every five minutes while it waits): its module, fingerprint,
	// line and why.
	BuildSaidEvent = "build.said"
	// BuilderLogDays is how long the log keeps its entries.
	BuilderLogDays = 30
	// BuildsSinceTool is the builder's tool answering every ended build since a time, in order (clause 9): its
	// argument `since` (RFC 3339), its answer BuildsSince.
	BuildsSinceTool = "builder_builds_since"
)

// BuildLogKey is the key of a module's entries in the builder's log: the module's name, refused when a log key could not
// hold it.
func BuildLogKey(module string) (string, error) {
	if err := keys.CheckName("module", module); err != nil {
		return "", err
	}
	return module, nil
}

// BuildLogEntry is one entry of the builder's log: the module, the fingerprint, the source revision, where the module is
// built from (its repository, its directory there, the commit and the ref), the build node and the time; at the end,
// the outcome, the manifest built (its digest, read from the indexer's state `manifests` under ManifestsKey), what it was
// built against (the bases' references, as the controller's built-before said them) and each artifact made
// (BuiltArtifact, the done key's: its name, kind, digest and reference). The repository, directory and commit are what
// the indexer's PathOf, the outside-built registrations and the assigner's running commits read; the manifest, against
// and made what the catalogue module registers a build from (the lead, 2026-10-29).
type BuildLogEntry struct {
	V          int             `json:"v"`
	Event      string          `json:"event"`
	Module     string          `json:"module"`
	FP         string          `json:"fp"`
	Source     string          `json:"source"`
	Repository string          `json:"repository"`
	Directory  string          `json:"directory"`
	Commit     string          `json:"commit"`
	Ref        string          `json:"ref,omitempty"`
	Node       string          `json:"node"`
	At         time.Time       `json:"at"`
	Outcome    string          `json:"outcome,omitempty"`
	Manifest   string          `json:"manifest,omitempty"`
	Against    []string        `json:"against,omitempty"`
	Made       []BuiltArtifact `json:"made,omitempty"`
	// Imports are, at a build's end, the mesh packages (import paths) the built programs import, their tests left out,
	// sorted and each once, as the build module answered them (BuildAnswer.Imports; novox/hq ADR 0593 §2): the indexer
	// keeps them on the module (KeptInputs2.Imports) when the build's fingerprint is the module's.
	Imports []string `json:"imports,omitempty"`
	// OutOfStep are, at a build's end, the generated files its test step found out of step with what their generator
	// writes, as the build module answered them (its test step's `out-of-step`): the indexer raises a finding naming them
	// for a trunk build, and only a clean build of the same module clears it. A start or a narration names none.
	OutOfStep []string `json:"out-of-step,omitempty"`
	// Line is a narration's words, Why what it narrates (asked, waiting, stored, refused): a build.said entry's alone.
	Line string `json:"line,omitempty"`
	Why  string `json:"why,omitempty"`
}

// BuildsSince is the answer of BuildsSinceTool: every ended build since a time, oldest first, and whether the log held
// more than one answer carries (then ask again from the last one's time).
type BuildsSince struct {
	Since  time.Time       `json:"since"`
	Builds []BuildLogEntry `json:"builds"`
	More   bool            `json:"more,omitempty"`
}

// NewestPerModule is each module's newest entry of entries (one kind, read from the last per subject or whole), by
// module: the reader's helper for the five newest and the running commits.
func NewestPerModule(entries []BuildLogEntry) map[string]BuildLogEntry {
	out := map[string]BuildLogEntry{}
	for _, e := range entries {
		if have, ok := out[e.Module]; !ok || e.At.After(have.At) {
			out[e.Module] = e
		}
	}
	return out
}

// EndedSince is, of entries, the ended builds at or after since, oldest first: the reader's helper for history and for
// BuildsSinceTool's answer.
func EndedSince(entries []BuildLogEntry, since time.Time) []BuildLogEntry {
	var out []BuildLogEntry
	for _, e := range entries {
		if e.Event == BuildEndedEvent && !e.At.Before(since) {
			out = append(out, e)
		}
	}
	sort.SliceStable(out, func(i, j int) bool { return out[i].At.Before(out[j].At) })
	return out
}

// EncodeBuildLogEntry is e as JSON at Version; it refuses an entry a reader could not place.
func EncodeBuildLogEntry(e BuildLogEntry) ([]byte, error) {
	e.V = keys.Version
	switch {
	case e.Event == BuildSaidEvent:
		switch {
		case e.Module == "" || e.FP == "" || e.At.IsZero() || e.Line == "":
			return nil, fmt.Errorf("builds: a build's narration names its module, fingerprint, line and time")
		case e.Outcome != "" || len(e.Made) > 0 || e.Manifest != "" || len(e.Against) > 0 || len(e.Imports) > 0 || len(e.OutOfStep) > 0:
			return nil, fmt.Errorf("builds: a build's narration names no outcome, manifest, base, artifact, import or file out of step")
		}
		return json.Marshal(e)
	case e.Event != BuildStartedEvent && e.Event != BuildEndedEvent:
		return nil, fmt.Errorf("builds: a build log entry is %s, %s or %s, not %q", BuildStartedEvent, BuildSaidEvent, BuildEndedEvent, e.Event)
	case e.Line != "" || e.Why != "":
		return nil, fmt.Errorf("builds: a build's start or end carries no narration's line")
	case e.Module == "" || e.FP == "" || e.Node == "" || e.At.IsZero() || e.Repository == "" || e.Commit == "":
		return nil, fmt.Errorf("builds: a build log entry names its module, fingerprint, repository, commit, node and time")
	case e.Event == BuildEndedEvent && e.Outcome == "":
		return nil, fmt.Errorf("builds: a build's end names its outcome")
	case e.Event == BuildStartedEvent && (e.Outcome != "" || len(e.Made) > 0 || e.Manifest != "" || len(e.Against) > 0 || len(e.Imports) > 0 ||
		len(e.OutOfStep) > 0):
		return nil, fmt.Errorf("builds: a build's start names no outcome, manifest, base, artifact, import or file out of step")
	}
	if err := trunk.CheckImports(e.Imports); err != nil {
		return nil, err
	}
	return json.Marshal(e)
}

// DecodeBuildLogEntry reads one entry.
func DecodeBuildLogEntry(data []byte) (BuildLogEntry, error) {
	var e BuildLogEntry
	if err := json.Unmarshal(data, &e); err != nil {
		return BuildLogEntry{}, fmt.Errorf("builds: a build log entry is not readable: %w", err)
	}
	if e.V != keys.Version {
		return BuildLogEntry{}, fmt.Errorf("builds: a build log entry of version %d, and this reads %d", e.V, keys.Version)
	}
	return e, nil
}

// BuildDuration is a build's duration, its end less its start (clause 1): false unless both are the same module's
// build of the same fingerprint, the start first.
func BuildDuration(start, end BuildLogEntry) (time.Duration, bool) {
	if start.Event != BuildStartedEvent || end.Event != BuildEndedEvent || start.Module != end.Module || start.FP != end.FP ||
		end.At.Before(start.At) {
		return 0, false
	}
	return end.At.Sub(start.At), true
}

// IsBuildEntry says whether an entry of the builder's log is a build's start or end, read from its event alone, so an entry of
// another kind (a build's narration, build.said) is passed over before its form is read. One whose event cannot be read is
// taken as a build's, so its decoding says what is wrong with it.
func IsBuildEntry(value []byte) bool {
	var e struct {
		Event *string `json:"event"`
	}
	if json.Unmarshal(value, &e) != nil || e.Event == nil {
		return true
	}
	return *e.Event == BuildStartedEvent || *e.Event == BuildEndedEvent
}