package operations

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

	"orchestra/internal/authz"
	"orchestra/internal/domain"
	"orchestra/internal/registry"
	"orchestra/internal/store"
	"orchestra/internal/workphase"
)

// ErrPlanPhase reports that a verification request cannot proceed. The reason
// is always specific, because it is delivered to a live implementer that has
// to act on it.
var ErrPlanPhase = fmt.Errorf("plan phase verification refused")

// VerificationRun is the outcome of one command the worker executed.
type VerificationRun struct {
	Command  []string `json:"command"`
	ExitCode int      `json:"exit_code"`
	Output   string   `json:"output,omitempty"`
}

// PlanPhaseCommands resolves the commands a phase's verification will run.
//
// The commands come from the accepted plan, never from the request. An
// implementer asks to verify a phase; what that phase is checked with was
// settled when the plan was sealed, so a request cannot smuggle in a command
// the planner did not write.
//
// Every command is checked against the project's policy before any of them
// runs. A partial execution followed by a refusal would leave side effects
// behind with nothing recording them.
func PlanPhaseCommands(s *store.Store, project registry.Project, taskID, phaseID string) (workphase.PlanPhase, error) {
	t, ok := s.Task(taskID)
	if !ok {
		return workphase.PlanPhase{}, domain.ErrNotFound
	}
	if t.PlanRef == "" {
		return workphase.PlanPhase{}, fmt.Errorf("%w: this task has no accepted plan", ErrPlanPhase)
	}
	raw, err := s.Artifact(t.PlanRef)
	if err != nil {
		return workphase.PlanPhase{}, fmt.Errorf("read accepted plan: %w", err)
	}
	doc, err := workphase.DecodeStoredPlan(raw)
	if err != nil {
		return workphase.PlanPhase{}, fmt.Errorf("read accepted plan: %w", err)
	}
	if len(doc.Phases) == 0 {
		// A plan sealed before plan.md names no executable unit. Saying so is
		// the honest answer; inventing a phase would make progress against a
		// plan that never had any.
		return workphase.PlanPhase{}, fmt.Errorf("%w: the accepted plan predates plan.md and declares no phases, so phase progress does not apply to it", ErrPlanPhase)
	}
	phase, ok := doc.Phase(phaseID)
	if !ok {
		return workphase.PlanPhase{}, fmt.Errorf("%w: the accepted plan has no %s; it has %s", ErrPlanPhase, phaseID, phaseNames(doc))
	}
	for _, argv := range phase.Automated {
		if allowed, why := project.Verification.Allows(argv); !allowed {
			// Refused before anything ran. The planner wrote a command the
			// project does not permit, and the implementer is told rather
			// than left retrying a phase that can never verify.
			return workphase.PlanPhase{}, fmt.Errorf("%w: %s declares a command %s cannot run: %s", ErrPlanPhase, phaseID, project.ID, why)
		}
	}
	return phase, nil
}

func phaseNames(doc workphase.PlanDoc) string {
	out := make([]string, 0, len(doc.Phases))
	for _, p := range doc.Phases {
		out = append(out, p.ID)
	}
	return strings.Join(out, ", ")
}

// RecordPlanPhaseVerification establishes what the runs prove, and appends the
// durable record.
//
// The status is derived here and never taken from the caller. An implementer
// may request verification; only this function decides whether a phase is
// verified, awaiting a human, or still in progress.
func RecordPlanPhaseVerification(s *store.Store, project registry.Project, taskID, phaseID, atSHA string, runs []VerificationRun) (domain.Event, error) {
	t, ok := s.Task(taskID)
	if !ok {
		return domain.Event{}, domain.ErrNotFound
	}
	if len(atSHA) != 40 {
		return domain.Event{}, fmt.Errorf("%w: verification must name the commit it ran against", ErrPlanPhase)
	}
	phase, err := PlanPhaseCommands(s, project, taskID, phaseID)
	if err != nil {
		return domain.Event{}, err
	}
	if len(runs) != len(phase.Automated) {
		return domain.Event{}, fmt.Errorf("%w: %s declares %d automated commands but %d results were reported", ErrPlanPhase, phaseID, len(phase.Automated), len(runs))
	}
	record := domain.PlanPhaseRecord{
		PlanRef: t.PlanRef, PhaseID: phaseID, AtSHA: atSHA,
		Status: domain.PlanPhaseVerified, At: time.Now().UTC(),
	}
	for i, r := range runs {
		// The result must describe the command the plan named. A reordered or
		// substituted result would attribute one command's exit code to
		// another.
		if strings.Join(r.Command, "\x00") != strings.Join(phase.Automated[i], "\x00") {
			return domain.Event{}, fmt.Errorf("%w: result %d reports %q but the plan declares %q", ErrPlanPhase, i, strings.Join(r.Command, " "), strings.Join(phase.Automated[i], " "))
		}
		record.Commands = append(record.Commands, r.Command)
		record.ExitCodes = append(record.ExitCodes, r.ExitCode)
		if r.ExitCode != 0 {
			record.Status = domain.PlanPhaseInProgress
		}
	}
	if record.Status == domain.PlanPhaseVerified && len(phase.Manual) > 0 {
		// Automated checks passing is not the whole phase. A human owns the
		// manual steps, and the phase waits rather than claiming more than
		// was established.
		record.Status = domain.PlanPhaseAwaitingManual
	}
	if record.Status != domain.PlanPhaseInProgress && manuallySignedOff(s, t, phaseID) {
		record.Status = domain.PlanPhaseVerified
	}
	if ref, err := s.PutArtifact(verificationEvidence(runs)); err == nil {
		record.EvidenceRef = ref
	} else {
		return domain.Event{}, fmt.Errorf("store verification evidence: %w", err)
	}
	payload := map[string]any{
		"plan_ref": record.PlanRef, "phase_id": record.PhaseID, "status": string(record.Status),
		"commands": record.Commands, "exit_codes": record.ExitCodes, "at_sha": record.AtSHA,
		"evidence_ref": record.EvidenceRef, "at": record.At,
	}
	if t.Lease != nil {
		payload["harness_id"], payload["lease_epoch"] = t.Lease.HarnessID, t.Lease.Epoch
	}
	b, err := json.Marshal(payload)
	if err != nil {
		return domain.Event{}, err
	}
	e := domain.Event{ID: domain.NewID(), Type: domain.EventPlanPhaseVerified, TaskID: taskID, Version: t.Version + 1, Payload: b, Surface: string(authz.System)}
	return e, s.Append(e)
}

// manuallySignedOff reports whether a human has already approved this exact
// phase of this exact plan. The subject carries both, so a later "looks good"
// on an unrelated thread cannot satisfy a gate nobody was discussing.
func manuallySignedOff(s *store.Store, t domain.Task, phaseID string) bool {
	intent, err := s.EffectiveIntent(t.ID)
	if err != nil {
		return false
	}
	subject := domain.PlanPhaseSubject(t.PlanRef, phaseID)
	for _, d := range intent.Decisions {
		if d.Subject == subject {
			return true
		}
	}
	return false
}

func verificationEvidence(runs []VerificationRun) []byte {
	b, _ := json.Marshal(runs)
	return b
}