package host

import (
	"context"
	"strings"

	"github.com/carlosframework/platform/internal/hostbox"
	"github.com/carlosframework/platform/internal/hostclaim"
	"github.com/carlosframework/platform/internal/park"
	"github.com/carlosframework/platform/internal/provision"
	"github.com/carlosframework/platform/internal/release"
)

// The park fakes the moves tests inject (Plan 5 Task 9a). Production has no
// stand-in for the claim's view or authorizers; these are the rules the
// stand-ins had, kept for the tests that do not exercise the real view
// (movesParkView, movessources_test.go). The rest is the claim's own, as
// claim Plan 12 landed it (Q10): the claim's lease set and AggregateLeases over the tests' lease
// table, park.Engine.RunHeld, and the MoveParks local authorizer's wrapper.

// standInView is the tests' park view: the location's objects classified by
// key, seen from region, and the other side of the move authoritative, which
// §5.1's table says it is before this side's probe is admitted (every install
// phase). role names this side (ruling J24): a landing (roleTarget) works
// while the source's region, From, is authoritative; a dirty return
// (roleSource) while the target's, To, is.
func standInView(region, role string, m *provision.MoveState) func(context.Context, hostclaim.Observed) (park.View, error) {
	return func(_ context.Context, obs hostclaim.Observed) (park.View, error) {
		if obs.Absent || obs.Claim == nil || obs.Claim.Holder == nil || m == nil {
			return park.View{}, park.ErrUnsafe
		}
		var authoritative string
		switch role {
		case roleTarget:
			authoritative = park.PlacementRegion(m.From)
		case roleSource:
			authoritative = park.PlacementRegion(m.To)
		default:
			return park.View{}, park.ErrUnsafe
		}
		location := strings.TrimSuffix(obs.Claim.Holder.Location, "/")
		return park.View{ClaimETag: obs.ETag, Region: region, AuthoritativeRegion: authoritative,
			GenerationOf: func(r park.Ref) (string, bool) { return landingGenerationOf(location, r.Key) }}, nil
	}
}

// recordView is standInView over the record's move as the store holds it
// when the engine asks.
func recordView(s release.Store, region, role string) func(context.Context, hostclaim.Observed) (park.View, error) {
	return func(ctx context.Context, obs hostclaim.Observed) (park.View, error) {
		if obs.Absent || obs.Claim == nil || obs.Claim.Holder == nil {
			return park.View{}, park.ErrUnsafe
		}
		h := obs.Claim.Holder
		rec, err := provision.GetRecord(ctx, s, h.Account, h.App, obs.Host)
		if err != nil {
			return park.View{}, err
		}
		return standInView(region, role, rec.Move)(ctx, obs)
	}
}

// allowParkAuthorize is the tests' claim authorizer: it allows every chore,
// so each arm's own operation check (movesArmAuthorize) decides alone.
func allowParkAuthorize(context.Context, hostclaim.Observed, hostclaim.Obligation) error { return nil }

// allowLocalAuthorize is the claim's MoveParks local authorizer
// (claimMoveLocalAuthorizer, M9) over an identity check that passes and the
// allowing owner: it allows every park-local and refuses anything else.
var allowLocalAuthorize = claimMoveLocalAuthorizer(func(context.Context) error { return nil }, allowParkAuthorize)

// claimParkLeases is the claim's park leases over the tests' lease table
// leases: AggregateLeases with the replica park lease set (M6), as the
// claim's MoveParks engine resolves them, lending a held lease to RunHeld.
func claimParkLeases(leases park.Leases) park.Leases {
	return hostbox.AggregateLeases{Leases: leases, Resolve: hostbox.ReplicaParkLeaseSet}
}

// armParkFakes arms c's park hooks: the claim's leases over the tests'
// lease table, the record-backed stand-in view for region and role, the
// allowing claim authorizer, park.Engine.RunHeld (movesRunHeld, M5) and the
// claim's local authorizer over the allowing owner.
func armParkFakes(c *moveCfg, s release.Store, leases park.Leases, region, role string) {
	c.ParkLeases = claimParkLeases(leases)
	c.ParkView = recordView(s, region, role)
	c.ParkAuthorize = allowParkAuthorize
	c.ParkRunHeld = movesRunHeld
	c.ParkLocalAuthorize = allowLocalAuthorize
}