package domain

import (
	"fmt"
	"strings"
	"time"
)

// EventPlanPhaseVerified records that Orchestra ran a plan phase's automated
// verification and what happened. The implementer never emits it: an agent may
// request verification, and only the plane can establish it.
const EventPlanPhaseVerified = "PlanPhaseVerified"

// PlanPhaseStatus is what Orchestra established about one phase.
type PlanPhaseStatus string

const (
	// PlanPhaseInProgress is the default and the outcome of a failed run. It
	// is never written by a request, only left in place by one.
	PlanPhaseInProgress PlanPhaseStatus = "in_progress"
	// PlanPhaseAwaitingManual means every automated check passed and manual
	// steps remain. A human signs those off; the agent cannot.
	PlanPhaseAwaitingManual PlanPhaseStatus = "awaiting_manual_verification"
	// PlanPhaseVerified means nothing further is required for this phase.
	PlanPhaseVerified PlanPhaseStatus = "verified"
)

func (s PlanPhaseStatus) Valid() bool {
	switch s {
	case PlanPhaseInProgress, PlanPhaseAwaitingManual, PlanPhaseVerified:
		return true
	}
	return false
}

// PlanPhaseRequestStatus is the single value an implementer may write. Every
// other status is a conclusion Orchestra reaches, so allowing an agent to
// assert one would let it declare its own work verified.
const PlanPhaseRequestStatus = "ready_for_verification"

// PlanPhaseRecord is one verification run, bound to the plan it belongs to and
// the commit it ran against.
//
// Both bindings are load-bearing. Without PlanRef, a phase verified under plan
// A survives into plan B, which is the same class of bug as a review that
// outlives the commit it examined. Without AtSHA, "verified" outlives the code
// that made it true.
type PlanPhaseRecord struct {
	PlanRef   string          `json:"plan_ref"`
	PhaseID   string          `json:"phase_id"`
	Status    PlanPhaseStatus `json:"status"`
	Commands  [][]string      `json:"commands,omitempty"`
	ExitCodes []int           `json:"exit_codes,omitempty"`
	AtSHA     string          `json:"at_sha"`
	// EvidenceRef is the CAS ref of the captured command output.
	EvidenceRef string    `json:"evidence_ref,omitempty"`
	At          time.Time `json:"at"`
	// ManualAtSHA is the tree a human was actually looking at when they signed
	// this phase off. A manual check on most projects is a human reading
	// output, so a sign-off establishes something about one tree and nothing
	// about the next one (F63). Rerunning the automated half re-establishes it
	// at the new commit; the manual half has to be given again, and this is
	// what makes the difference visible instead of assumed.
	ManualAtSHA string `json:"manual_at_sha,omitempty"`
}

// Stale reports whether the tree has moved since this phase was verified. A
// stale record is retained and labelled rather than discarded: it is still
// true that the phase passed at that commit, and hiding it would lose the
// provenance. What it must never do is read as current.
func (r PlanPhaseRecord) Stale(headSHA string) bool {
	return headSHA != "" && r.AtSHA != "" && r.AtSHA != headSHA
}

// PlanProgress is the durable verification state for one accepted plan.
type PlanProgress struct {
	// PlanRef is the plan these records belong to. A record from a superseded
	// plan is never counted, so a replan cannot inherit progress it did not
	// earn.
	PlanRef string            `json:"plan_ref"`
	Phases  []PlanPhaseRecord `json:"phases,omitempty"`
}

// PlanPhases returns the records that belong to the currently accepted plan.
// A task whose plan was superseded reports none, whatever the log still holds.
func (t Task) PlanPhases() []PlanPhaseRecord {
	if t.PlanProgress == nil || t.PlanRef == "" || t.PlanProgress.PlanRef != t.PlanRef {
		return nil
	}
	return t.PlanProgress.Phases
}

// PlanPhase returns the record for one phase of the accepted plan.
func (t Task) PlanPhase(id string) (PlanPhaseRecord, bool) {
	for _, r := range t.PlanPhases() {
		if r.PhaseID == id {
			return r, true
		}
	}
	return PlanPhaseRecord{}, false
}

// PlanPhaseSubject is the decision subject a manual sign-off carries. The key
// binds the approval to one phase of one plan, so a later "looks good" on an
// unrelated thread cannot satisfy a gate nobody was talking about.
func PlanPhaseSubject(planRef, phaseID string) string {
	return "plan_phase_verification:" + planRef + ":" + phaseID
}

const maxVerificationCommands = 16

func ValidatePlanPhaseVerified(p map[string]any) error {
	planRef, _ := p["plan_ref"].(string)
	if strings.TrimSpace(planRef) == "" {
		return fmt.Errorf("%w: plan_ref required", ErrInvalid)
	}
	phaseID, _ := p["phase_id"].(string)
	if strings.TrimSpace(phaseID) == "" {
		return fmt.Errorf("%w: phase_id required", ErrInvalid)
	}
	status, _ := p["status"].(string)
	if !PlanPhaseStatus(status).Valid() {
		return fmt.Errorf("%w: status %q is not a plan phase status", ErrInvalid, status)
	}
	if sha, _ := p["at_sha"].(string); len(sha) != 40 {
		return fmt.Errorf("%w: at_sha must be a full commit sha", ErrInvalid)
	}
	codes, _ := p["exit_codes"].([]any)
	if len(codes) > maxVerificationCommands {
		return fmt.Errorf("%w: %d exit codes exceeds the %d command bound", ErrInvalid, len(codes), maxVerificationCommands)
	}
	// A verified phase whose commands failed would be a contradiction the
	// reducer could not detect later.
	if PlanPhaseStatus(status) != PlanPhaseInProgress {
		for _, c := range codes {
			if code, ok := c.(float64); !ok || code != 0 {
				return fmt.Errorf("%w: status %q cannot carry a non-zero exit code", ErrInvalid, status)
			}
		}
	}
	return nil
}