package dehub

import (
	"bytes"
	"dehub/accessctl"
	"dehub/sigcred"
	"io"
	"math/rand"
	"path/filepath"
	"runtime/debug"
	"testing"

	"gopkg.in/src-d/go-git.v4"
	"gopkg.in/src-d/go-git.v4/plumbing"
	yaml "gopkg.in/yaml.v2"
)

type harness struct {
	t    *testing.T
	rand *rand.Rand
	repo *Repo
	cfg  *Config
	sig  sigcred.SignifierInterface
}

func newHarness(t *testing.T) *harness {
	rand := rand.New(rand.NewSource(0xb4eadb01))
	sig, pubKeyBody := sigcred.SignifierPGPTmp(rand)
	pubKeyPath := filepath.Join(DehubDir, "root.asc")

	cfg := &Config{
		Accounts: []Account{{
			ID: "root",
			Signifiers: []sigcred.Signifier{{PGPPublicKeyFile: &sigcred.SignifierPGPFile{
				Path: pubKeyPath,
			}}},
		}},
		AccessControls: []accessctl.BranchAccessControl{
			{
				BranchPattern: "**",
				ChangeAccessControls: []accessctl.ChangeAccessControl{
					{
						FilePathPattern: "**",
						Condition: accessctl.Condition{
							Signature: &accessctl.ConditionSignature{
								AccountIDs: []string{"root"},
								Count:      "100%",
							},
						},
					},
				},
			},
		},
	}
	cfgBody, err := yaml.Marshal(cfg)
	if err != nil {
		t.Fatal(err)
	}

	h := &harness{
		t:    t,
		rand: rand,
		repo: InitMemRepo(),
		cfg:  cfg,
		sig:  sig,
	}
	h.stage(map[string]string{
		ConfigPath: string(cfgBody),
		pubKeyPath: string(pubKeyBody),
	})

	return h
}

func (h *harness) stage(tree map[string]string) {
	w, err := h.repo.GitRepo.Worktree()
	if err != nil {
		h.t.Fatal(err)
	}
	fs := w.Filesystem
	for path, content := range tree {
		if content == "" {
			if _, err := w.Remove(path); err != nil {
				h.t.Fatalf("error removing %q: %v", path, err)
			}
			continue
		}

		dir := filepath.Dir(path)
		if err := fs.MkdirAll(dir, 0666); err != nil {
			h.t.Fatalf("error making directory %q: %v", dir, err)
		}

		f, err := fs.Create(path)
		if err != nil {
			h.t.Fatalf("error creating file %q: %v", path, err)

		} else if _, err := io.Copy(f, bytes.NewBufferString(content)); err != nil {
			h.t.Fatalf("error writing to file %q: %v", path, err)

		} else if err := f.Close(); err != nil {
			h.t.Fatalf("error closing file %q: %v", path, err)

		} else if _, err := w.Add(path); err != nil {
			h.t.Fatalf("error adding file %q to index: %v", path, err)
		}
	}
}

func (h *harness) changeCommit(msg, accountID string, sig sigcred.SignifierInterface) (Commit, plumbing.Hash) {
	commit, err := h.repo.NewCommitChange(msg)
	if err != nil {
		h.t.Fatalf("failed to create CommitChange: %v", err)
	}

	if sig != nil {
		if commit, err = h.repo.AccreditCommit(commit, accountID, sig); err != nil {
			h.t.Fatalf("failed to accredit commit: %v", err)
		}
	}

	hash, err := h.repo.Commit(commit, accountID)
	if err != nil {
		h.t.Fatalf("failed to commit ChangeCommit: %v", err)
	}

	return commit, hash
}

func (h *harness) reset(to plumbing.Hash, mode git.ResetMode) {
	w, err := h.repo.GitRepo.Worktree()
	if err != nil {
		h.t.Fatal(err)
	}

	err = w.Reset(&git.ResetOptions{
		Commit: to,
		Mode:   mode,
	})
	if err != nil {
		h.t.Fatal(err)
	}
}

func TestHasStagedChanges(t *testing.T) {
	harness := newHarness(t)
	assertHasStaged := func(expHasStaged bool) {
		hasStaged, err := harness.repo.HasStagedChanges()
		if err != nil {
			debug.PrintStack()
			t.Fatalf("error calling HasStagedChanges: %v", err)
		} else if hasStaged != expHasStaged {
			debug.PrintStack()
			t.Fatalf("expected HasStagedChanges to return %v", expHasStaged)
		}
	}

	// the harness starts with some staged changes
	assertHasStaged(true)

	harness.stage(map[string]string{"foo": "bar"})
	assertHasStaged(true)
	harness.changeCommit("first commit", "root", harness.sig)
	assertHasStaged(false)

	harness.stage(map[string]string{"foo": ""}) // delete foo
	assertHasStaged(true)
	harness.changeCommit("second commit", "root", harness.sig)
	assertHasStaged(false)
}

// TestOldConfig tests that having an older, now malformed, Config doesn't mess
// with the current parsing, as long as the default access controls still work.
func TestOldConfig(t *testing.T) {
	harness := newHarness(t)

	// overwrite the currently staged config file with an older form
	harness.stage(map[string]string{ConfigPath: `
---
accounts:
  - id: root
    signifiers:
      - type: pgp_public_key_file
        path: ".dehub/root.asc"

access_controls:
  - pattern: "**"
    condition:
      type: signature
      account_ids:
        - root
      count: 0
`})
	_, hash0 := harness.changeCommit("first commit, this is going great", "root", harness.sig)

	// even though that access_controls doesn't actually require any signatures,
	// it should be used because it's not well formed.
	harness.stage(map[string]string{"foo": "no rules!"})
	_, hash1 := harness.changeCommit("ain't no laws", "toot", nil)

	// verifying the first should work, but not the second.
	if err := harness.repo.VerifyCommit(MainRefName, hash0); err != nil {
		t.Fatalf("first commit %q should be verifiable, but got: %v", hash0, err)
	} else if err := harness.repo.VerifyCommit(MainRefName, hash1); err == nil {
		t.Fatalf("second commit %q should not have been verified", hash1)
	}

	// reset back to hash0
	harness.reset(hash0, git.HardReset)

	// make a commit fixing the config. everything should still be fine.
	harness.stage(map[string]string{ConfigPath: `
---
accounts:
  - id: root
    signifiers:
      - type: pgp_public_key_file
        path: ".dehub/root.asc"
`})
	_, hash2 := harness.changeCommit("Fix the config!", "root", harness.sig)
	if err := harness.repo.VerifyCommit(MainRefName, hash2); err != nil {
		t.Fatalf("config fix commit %q should be verifiable, but got: %v", hash2, err)
	}
}

// TestThisRepoStillVerifies opens this actual repository and ensures that all
// commits in it still verify, given this codebase.
func TestThisRepoStillVerifies(t *testing.T) {
	repo, err := OpenRepo(".")
	if err != nil {
		t.Fatalf("error opening repo: %v", err)
	}

	headCommit, _, err := repo.head()
	if err != nil {
		t.Fatalf("error getting repo head: %v", err)
	}

	checkedOutBranch, err := repo.CheckedOutBranch()
	if err != nil {
		t.Fatalf("error determining checked out branch: %v", err)
	}

	for _, hash := range headCommit.ParentHashes {
		if err := repo.VerifyCommit(checkedOutBranch, hash); err != nil {
			t.Fatalf("error verifying commit %q of branch %q: %v", hash, checkedOutBranch, err)
		}
	}
}