package cabana_test

import (
	"context"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"

	"git.golem15.com/golem15/summercms/modules/cabana"
	"git.golem15.com/golem15/summercms/modules/pact"
	"gorm.io/gorm"
)

const (
	// ledgerSettle is a Detached bulk action; ledgerSettleLocked is the same
	// action without Detached, the control.
	ledgerSettle       = "settle"
	ledgerSettleLocked = "settle_locked"
	// ledgerInvalid is the sentinel name settle refuses with a
	// cabana.ValidationError, after the earlier rows were written.
	ledgerInvalid = "Invalid"
)

// ledgerRun is what one Run of a settle action observed.
type ledgerRun struct {
	names []string
	// sawTx is whether cabana.TxFromContext reported a transaction.
	sawTx bool
	// lockErr is the error of another connection's SELECT ... FOR UPDATE
	// NOWAIT on each selected row, taken while Run held the records.
	lockErr []error
}

type ledgerSpy struct {
	mu   sync.Mutex
	runs []ledgerRun
}

func (s *ledgerSpy) add(r ledgerRun) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.runs = append(s.runs, r)
}

func (s *ledgerSpy) take() []ledgerRun {
	s.mu.Lock()
	defer s.mu.Unlock()
	out := s.runs
	s.runs = nil
	return out
}

// ledgerController is the roster controller with two more bulk actions,
// settle (Detached) and settle_locked, registered for this test only.
type ledgerController struct {
	rosterController
	spy *ledgerSpy
	db  *gorm.DB
}

func (c ledgerController) settle(detached bool) pact.AdminBulkAction {
	name := ledgerSettleLocked
	if detached {
		name = ledgerSettle
	}
	return pact.AdminBulkAction{
		Name: name, Label: "acme.roster::lang.people.activate",
		Permissions: []string{"acme.roster.access"},
		Detached:    detached,
		Run: func(ctx context.Context, in pact.AdminBulkActionInput) (pact.AdminBulkActionResult, error) {
			run := ledgerRun{names: rosterNames(in.Records)}
			tx, sawTx := cabana.TxFromContext(ctx)
			run.sawTx = sawTx
			for _, record := range in.Records {
				id := record.(*rosterPerson).ID
				run.lockErr = append(run.lockErr, c.db.Transaction(func(tx *gorm.DB) error {
					var got []uint
					return tx.Raw(`SELECT id FROM roster_people WHERE id = ? FOR UPDATE NOWAIT`, id).Scan(&got).Error
				}))
			}
			c.spy.add(run)
			changed := 0
			for _, record := range in.Records {
				person := record.(*rosterPerson)
				if person.Name == ledgerInvalid {
					return pact.AdminBulkActionResult{}, &cabana.ValidationError{Details: map[string]any{"name": []string{"refused by the test"}}}
				}
				// A detached Run makes its own short write; the locked
				// control writes through the framework transaction, which
				// holds the row lock.
				write := c.db.WithContext(ctx)
				if sawTx {
					write = tx
				}
				if err := write.Unscoped().Model(&rosterPerson{}).Where("id = ?", person.ID).Update("active", true).Error; err != nil {
					return pact.AdminBulkActionResult{}, err
				}
				changed++
			}
			return pact.AdminBulkActionResult{Affected: changed}, nil
		},
	}
}

func (c ledgerController) AdminBulkActions() []pact.AdminBulkAction {
	return append(c.rosterController.AdminBulkActions(), c.settle(true), c.settle(false))
}

// newLedgerEnv is the roster environment whose people list also declares
// settle and settle_locked.
func newLedgerEnv(t *testing.T) (*rosterEnv, *gorm.DB, *ledgerSpy) {
	t.Helper()
	list := "controllers/people/config_list.yaml"
	raw, err := os.ReadFile(filepath.Join(rosterDir, list))
	if err != nil {
		t.Fatal(err)
	}
	const declared = "bulkActions: [activate, archive]"
	if !strings.Contains(string(raw), declared) {
		t.Fatalf("%s does not declare %q", list, declared)
	}
	body := strings.Replace(string(raw), declared, "bulkActions: [activate, archive, "+ledgerSettle+", "+ledgerSettleLocked+"]", 1)
	spy := &ledgerSpy{}
	env, gdb := newRosterEnvWith(t, func(p *rosterPlugin) {
		p.fsys = rosterTree(t, map[string]string{list: body})
		db := p.db
		p.wrap = func(ctl rosterController) pact.AdminController {
			return ledgerController{rosterController: ctl, spy: spy, db: db}
		}
	})
	return env, gdb, spy
}

// TestDetachedBulkAction covers pact.AdminBulkAction.Detached on Postgres
// (gap closure 18.1-08, WR-01): a detached Run sees no transaction on the
// context and holds no row lock (another connection's SELECT ... FOR UPDATE
// NOWAIT on a selected row succeeds while Run runs); the empty, absent and
// partial-selection rules are those of the locked path; a ValidationError
// from Run is 422 and the rows Run wrote before it stay written; the same
// action without Detached still runs in a transaction that holds the row
// locks.
func TestDetachedBulkAction(t *testing.T) {
	env, gdb, spy := newLedgerEnv(t)
	settle := rosterPeople + "/bulk/" + ledgerSettle
	settleLocked := rosterPeople + "/bulk/" + ledgerSettleLocked

	t.Run("Run sees no transaction and holds no row lock", func(t *testing.T) {
		ada := rosterInsert(t, gdb, rosterPerson{Tenant: "acme", Name: "Ada"})
		bob := rosterInsert(t, gdb, rosterPerson{Tenant: "acme", Name: "Bob"})
		rec := env.expect(t, http.StatusOK, http.MethodPost, settle, rosterIDs(bob, ada), "bearer")
		if result := rosterBulkResult(t, rec); result.Affected != 2 {
			t.Fatalf("affected = %d, want 2", result.Affected)
		}
		runs := spy.take()
		if len(runs) != 1 || strings.Join(runs[0].names, ",") != "Ada,Bob" {
			t.Fatalf("runs %+v, want one over Ada and Bob in id order", runs)
		}
		if runs[0].sawTx {
			t.Fatal("a detached Run found a transaction on the context")
		}
		for i, err := range runs[0].lockErr {
			if err != nil {
				t.Fatalf("row %d was locked during a detached Run: %v", i, err)
			}
		}
		if !rosterLoad(t, gdb, ada).Active || !rosterLoad(t, gdb, bob).Active {
			t.Fatal("the detached writes were not stored")
		}
	})

	t.Run("an empty selection is 422 and an absent one is affected 0, without Run", func(t *testing.T) {
		rec := env.expect(t, http.StatusUnprocessableEntity, http.MethodPost, settle, `{"ids":[]}`, "bearer")
		actErrorCode(t, rec.Body.Bytes(), "validation_failed")
		rec = env.expect(t, http.StatusOK, http.MethodPost, settle, rosterIDs(999998, 999999), "bearer")
		if result := rosterBulkResult(t, rec); result.Affected != 0 || result.Message != "" {
			t.Fatalf("absent selection: %+v", result)
		}
		if runs := spy.take(); len(runs) != 0 {
			t.Fatalf("Run was called: %+v", runs)
		}
	})

	t.Run("a partial selection is 409 without Run", func(t *testing.T) {
		own := rosterInsert(t, gdb, rosterPerson{Tenant: "acme", Name: "Own"})
		foreign := rosterInsert(t, gdb, rosterPerson{Tenant: "other", Name: "Foreign"})
		rec := env.expect(t, http.StatusConflict, http.MethodPost, settle, rosterIDs(own, foreign), "bearer")
		actErrorCode(t, rec.Body.Bytes(), "conflict")
		if runs := spy.take(); len(runs) != 0 {
			t.Fatalf("Run was called for a partial selection: %+v", runs)
		}
		if rosterLoad(t, gdb, own).Active || rosterLoad(t, gdb, foreign).Active {
			t.Fatal("a partial selection changed a row")
		}
	})

	t.Run("a ValidationError is 422 and earlier writes stay", func(t *testing.T) {
		first := rosterInsert(t, gdb, rosterPerson{Tenant: "acme", Name: "First"})
		invalid := rosterInsert(t, gdb, rosterPerson{Tenant: "acme", Name: ledgerInvalid})
		rec := env.expect(t, http.StatusUnprocessableEntity, http.MethodPost, settle, rosterIDs(first, invalid), "bearer")
		actErrorCode(t, rec.Body.Bytes(), "validation_failed")
		if runs := spy.take(); len(runs) != 1 {
			t.Fatalf("runs %+v, want 1", runs)
		}
		if !rosterLoad(t, gdb, first).Active {
			t.Fatal("a detached action's write before its failure was rolled back")
		}
		if rosterLoad(t, gdb, invalid).Active {
			t.Fatal("the refused row was written")
		}
	})

	t.Run("without Detached Run holds a transaction and the row locks", func(t *testing.T) {
		carl := rosterInsert(t, gdb, rosterPerson{Tenant: "acme", Name: "Carl"})
		env.expect(t, http.StatusOK, http.MethodPost, settleLocked, rosterIDs(carl), "bearer")
		runs := spy.take()
		if len(runs) != 1 || !runs[0].sawTx {
			t.Fatalf("runs %+v, want one inside the framework transaction", runs)
		}
		if len(runs[0].lockErr) != 1 || runs[0].lockErr[0] == nil || !strings.Contains(runs[0].lockErr[0].Error(), "55P03") {
			t.Fatalf("NOWAIT during a locked Run: %v, want lock_not_available (55P03)", runs[0].lockErr)
		}
	})
}