package dehub

import (
	"bytes"
	"dehub/sigcred"
	"errors"
	"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("root", rand)
	pubKeyPath := filepath.Join(DehubDir, "root.asc")

	cfg := &Config{
		Accounts: []Account{{
			ID: "root",
			Signifiers: []sigcred.Signifier{{PGPPublicKeyFile: &sigcred.SignifierPGPFile{
				Path: pubKeyPath,
			}}},
		}},
	}
	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) stageCfg() {
	cfgBody, err := yaml.Marshal(h.cfg)
	if err != nil {
		h.t.Fatal(err)
	}
	h.stage(map[string]string{ConfigPath: string(cfgBody)})
}

func (h *harness) checkout(branch plumbing.ReferenceName) {
	w, err := h.repo.GitRepo.Worktree()
	if err != nil {
		h.t.Fatal(err)
	}

	head, err := h.repo.GetGitHead()
	if err != nil {
		h.t.Fatal(err)
	}

	_, err = h.repo.GitRepo.Storer.Reference(branch)
	if errors.Is(err, plumbing.ErrReferenceNotFound) {
		err = w.Checkout(&git.CheckoutOptions{
			Hash:   head.GitCommit.Hash,
			Branch: branch,
			Create: true,
		})
	} else if err != nil {
		h.t.Fatalf("checking if branch already exists: %v", branch)
	} else {
		err = w.Checkout(&git.CheckoutOptions{
			Branch: branch,
		})
	}

	if err != nil {
		h.t.Fatalf("checking out branch: %v", err)
	}
}

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 (h *harness) tryCommit(
	shouldSucceed bool,
	commit Commit,
	accountID string, accountSig sigcred.SignifierInterface,
) GitCommit {
	if accountSig != nil {
		var err error
		if commit, err = h.repo.AccreditCommit(commit, accountSig); err != nil {
			h.t.Fatalf("accrediting commit: %v", err)
		}
	}

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

	branch, err := h.repo.ReferenceToBranchName(plumbing.HEAD)
	if err != nil {
		h.t.Fatalf("determining checked out branch: %v", err)
	}

	err = h.repo.VerifyCommits(branch, []GitCommit{gitCommit})
	if shouldSucceed && err != nil {
		h.t.Fatalf("verifying commit %q: %v", gitCommit.GitCommit.Hash, err)
	} else if shouldSucceed {
		return gitCommit
	} else if !shouldSucceed && err == nil {
		h.t.Fatalf("verifying commit %q should have failed", gitCommit.GitCommit.Hash)
	}

	if gitCommit.GitCommit.NumParents() == 0 {
		h.t.Fatalf("unverifiable commit %q has no parents, but it should", gitCommit.GitCommit.Hash)
	}

	h.reset(gitCommit.GitCommit.ParentHashes[0], git.HardReset)
	return gitCommit
}

func (h *harness) changeCommit(
	msg string,
	accountID string,
	sig sigcred.SignifierInterface,
) GitCommit {
	commit, err := h.repo.NewCommitChange(msg)
	if err != nil {
		h.t.Fatalf("creating ChangeCommit: %v", err)
	}
	return h.tryCommit(true, commit, accountID, sig)
}

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
`})

	// this commit should be created and verify fine
	harness.changeCommit("first commit, this is going great", "root", harness.sig)

	// this commit should not be verifiable, because toot isn't in accounts and
	// the default access controls should be being used
	harness.stage(map[string]string{"foo": "no rules!"})
	badCommit, err := harness.repo.NewCommitChange("ain't no laws")
	if err != nil {
		t.Fatalf("creating CommitChange: %v", err)
	}
	harness.tryCommit(false, badCommit, "toot", nil)

	// 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"
`})
	harness.changeCommit("Fix the config!", "root", harness.sig)
}

// 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)
	}

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

	allCommits, err := repo.GetGitCommitRange(plumbing.ZeroHash, headGitCommit.GitCommit.Hash)
	if err != nil {
		t.Fatalf("getting all commits (up to %q): %v",
			headGitCommit.GitCommit.Hash, err)
	}

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

	if err := repo.VerifyCommits(checkedOutBranch, allCommits); err != nil {
		t.Fatal(err)
	}
}