// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package project

import (
	"bytes"
	"context"
	"encoding/xml"
	"fmt"
	"hash/fnv"
	"io"
	"io/ioutil"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strings"
	"time"

	"fuchsia.googlesource.com/jiri"
	"fuchsia.googlesource.com/jiri/envvar"
	"fuchsia.googlesource.com/jiri/retry"
)

// Manifest represents a setting used for updating the universe.
type Manifest struct {
	Imports      []Import      `xml:"imports>import"`
	LocalImports []LocalImport `xml:"imports>localimport"`
	Projects     []Project     `xml:"projects>project"`
	Hooks        []Hook        `xml:"hooks>hook"`
	XMLName      struct{}      `xml:"manifest"`
}

// ManifestFromBytes returns a manifest parsed from data, with defaults filled
// in.
func ManifestFromBytes(data []byte) (*Manifest, error) {
	m := new(Manifest)
	if len(data) > 0 {
		if err := xml.Unmarshal(data, m); err != nil {
			return nil, err
		}
	}
	if err := m.fillDefaults(); err != nil {
		return nil, err
	}
	return m, nil
}

// ManifestFromFile returns a manifest parsed from the contents of filename,
// with defaults filled in.
//
// Note that unlike ProjectFromFile, ManifestFromFile does not convert project
// paths to absolute paths because it's possible to load a manifest with a
// specific root directory different from jirix.Root.  The usual way to load a
// manifest is through LoadManifest, which does absolutize the paths, and uses
// the correct root directory.
func ManifestFromFile(jirix *jiri.X, filename string) (*Manifest, error) {
	data, err := ioutil.ReadFile(filename)
	if err != nil {
		return nil, fmtError(err)
	}
	m, err := ManifestFromBytes(data)
	if err != nil {
		return nil, fmt.Errorf("invalid manifest %s: %v", filename, err)
	}
	return m, nil
}

var (
	newlineBytes       = []byte("\n")
	emptyImportsBytes  = []byte("\n  <imports></imports>\n")
	emptyProjectsBytes = []byte("\n  <projects></projects>\n")
	emptyHooksBytes    = []byte("\n  <hooks></hooks>\n")

	endElemBytes        = []byte("/>\n")
	endImportBytes      = []byte("></import>\n")
	endLocalImportBytes = []byte("></localimport>\n")
	endProjectBytes     = []byte("></project>\n")
	endHookBytes        = []byte("></hook>\n")

	endImportSoloBytes  = []byte("></import>")
	endProjectSoloBytes = []byte("></project>")
	endElemSoloBytes    = []byte("/>")
)

// deepCopy returns a deep copy of Manifest.
func (m *Manifest) deepCopy() *Manifest {
	x := new(Manifest)
	x.Imports = append([]Import(nil), m.Imports...)
	x.LocalImports = append([]LocalImport(nil), m.LocalImports...)
	x.Projects = append([]Project(nil), m.Projects...)
	x.Hooks = append([]Hook(nil), m.Hooks...)
	return x
}

// ToBytes returns m as serialized bytes, with defaults unfilled.
func (m *Manifest) ToBytes() ([]byte, error) {
	m = m.deepCopy() // avoid changing manifest when unfilling defaults.
	if err := m.unfillDefaults(); err != nil {
		return nil, err
	}
	data, err := xml.MarshalIndent(m, "", "  ")
	if err != nil {
		return nil, fmt.Errorf("manifest xml.Marshal failed: %v", err)
	}
	// It's hard (impossible?) to get xml.Marshal to elide some of the empty
	// elements, or produce short empty elements, so we post-process the data.
	data = bytes.Replace(data, emptyImportsBytes, newlineBytes, -1)
	data = bytes.Replace(data, emptyProjectsBytes, newlineBytes, -1)
	data = bytes.Replace(data, emptyHooksBytes, newlineBytes, -1)
	data = bytes.Replace(data, endImportBytes, endElemBytes, -1)
	data = bytes.Replace(data, endLocalImportBytes, endElemBytes, -1)
	data = bytes.Replace(data, endProjectBytes, endElemBytes, -1)
	data = bytes.Replace(data, endHookBytes, endElemBytes, -1)
	if !bytes.HasSuffix(data, newlineBytes) {
		data = append(data, '\n')
	}
	return data, nil
}

// ToFile writes the manifest m to a file with the given filename, with
// defaults unfilled and all project paths relative to the jiri root.
func (m *Manifest) ToFile(jirix *jiri.X, filename string) error {
	// Replace absolute paths with relative paths to make it possible to move
	// the root directory locally.
	projects := []Project{}
	for _, project := range m.Projects {
		if err := project.relativizePaths(jirix.Root); err != nil {
			return err
		}
		projects = append(projects, project)
	}
	// Sort the projects and hooks to ensure that the output of "jiri
	// snapshot" is deterministic.  Sorting the hooks by name allows
	// some control over the ordering of the hooks in case that is
	// necessary.
	sort.Sort(ProjectsByPath(projects))
	m.Projects = projects
	sort.Sort(HooksByName(m.Hooks))
	data, err := m.ToBytes()
	if err != nil {
		return err
	}
	return safeWriteFile(jirix, filename, data)
}

func (m *Manifest) fillDefaults() error {
	for index := range m.Imports {
		if err := m.Imports[index].fillDefaults(); err != nil {
			return err
		}
	}
	for index := range m.LocalImports {
		if err := m.LocalImports[index].validate(); err != nil {
			return err
		}
	}
	for index := range m.Projects {
		if err := m.Projects[index].fillDefaults(); err != nil {
			return err
		}
	}
	return nil
}

func (m *Manifest) unfillDefaults() error {
	for index := range m.Imports {
		if err := m.Imports[index].unfillDefaults(); err != nil {
			return err
		}
	}
	for index := range m.LocalImports {
		if err := m.LocalImports[index].validate(); err != nil {
			return err
		}
	}
	for index := range m.Projects {
		if err := m.Projects[index].unfillDefaults(); err != nil {
			return err
		}
	}
	return nil
}

// Import represents a remote manifest import.
type Import struct {
	// Manifest file to use from the remote manifest project.
	Manifest string `xml:"manifest,attr,omitempty"`
	// Name is the name of the remote manifest project, used to determine the
	// project key.
	Name string `xml:"name,attr,omitempty"`
	// Remote is the remote manifest project to import.
	Remote string `xml:"remote,attr,omitempty"`
	// Revision is the revison to checkout,
	// this takes precedence over RemoteBranch
	Revision string `xml:"revision,attr,omitempty"`
	// RemoteBranch is the name of the remote branch to track.
	RemoteBranch string `xml:"remotebranch,attr,omitempty"`
	// Root path, prepended to all project paths specified in the manifest file.
	Root    string   `xml:"root,attr,omitempty"`
	XMLName struct{} `xml:"import"`
}

func (i *Import) fillDefaults() error {
	if i.RemoteBranch == "" {
		i.RemoteBranch = "master"
	}
	if i.Revision == "" {
		i.Revision = "HEAD"
	}
	return i.validate()
}

func (i *Import) unfillDefaults() error {
	if i.RemoteBranch == "master" {
		i.RemoteBranch = ""
	}
	if i.Revision == "HEAD" {
		i.Revision = ""
	}
	return i.validate()
}

func (i *Import) validate() error {
	if i.Manifest == "" || i.Remote == "" {
		return fmt.Errorf("bad import: both manifest and remote must be specified")
	}
	return nil
}

func (i *Import) toProject(path string) (Project, error) {
	p := Project{
		Name:         i.Name,
		Path:         path,
		Remote:       i.Remote,
		Revision:     i.Revision,
		RemoteBranch: i.RemoteBranch,
	}
	err := p.fillDefaults()
	return p, err
}

// ProjectKey returns the unique ProjectKey for the imported project.
func (i *Import) ProjectKey() ProjectKey {
	return MakeProjectKey(i.Name, i.Remote)
}

// projectKeyFileName returns a file name based on the ProjectKey.
func (i *Import) projectKeyFileName() string {
	// TODO(toddw): Disallow weird characters from project names.
	hash := fnv.New64a()
	hash.Write([]byte(i.ProjectKey()))
	return fmt.Sprintf("%s_%x", i.Name, hash.Sum64())
}

// cycleKey returns a key based on the remote and manifest, used for
// cycle-detection.  It's only valid for new-style remote imports; it's empty
// for the old-style local imports.
func (i *Import) cycleKey() string {
	if i.Remote == "" {
		return ""
	}
	// We don't join the remote and manifest with a slash or any other url-safe
	// character, since that might not be unique.  E.g.
	//   remote:   https://foo.com/a/b    remote:   https://foo.com/a
	//   manifest: c                      manifest: b/c
	// In both cases, the key would be https://foo.com/a/b/c.
	return i.Remote + " + " + i.Manifest
}

// LocalImport represents a local manifest import.
type LocalImport struct {
	// Manifest file to import from.
	File    string   `xml:"file,attr,omitempty"`
	XMLName struct{} `xml:"localimport"`
}

func (i *LocalImport) validate() error {
	if i.File == "" {
		return fmt.Errorf("bad localimport: must specify file: %+v", *i)
	}
	return nil
}

type LocalConfig struct {
	Ignore   bool     `xml:"ignore"`
	NoUpdate bool     `xml:"no-update"`
	NoRebase bool     `xml:"no-rebase"`
	XMLName  struct{} `xml:"config"`
}

// Reads localConfig from given reader. Returns incorrect bytes
func (lc *LocalConfig) ReadFrom(r io.Reader) (int64, error) {
	return 1, xml.NewDecoder(r).Decode(lc)
}

func LocalConfigFromFile(jirix *jiri.X, filename string) (LocalConfig, error) {
	var lc LocalConfig
	f, err := os.Open(filename)
	if os.IsNotExist(err) {
		return lc, nil
	} else if err != nil {
		return lc, fmtError(err)
	}
	_, err = lc.ReadFrom(f)
	return lc, err
}

// Writes the localConfig to given writer. Returns incorrect bytes
func (lc *LocalConfig) WriteTo(writer io.Writer) (int64, error) {
	encoder := xml.NewEncoder(writer)
	encoder.Indent("", " ")
	return 1, encoder.Encode(lc)
}

func (lc *LocalConfig) ToFile(jirix *jiri.X, filename string) error {
	if err := os.MkdirAll(filepath.Dir(filename), 0755); err != nil {
		return fmtError(err)
	}
	writer, err := os.Create(filename)
	if err != nil {
		return fmtError(err)
	}
	defer writer.Close()
	_, err = lc.WriteTo(writer)
	return err
}

func WriteLocalConfig(jirix *jiri.X, project Project, lc LocalConfig) error {
	configFile := filepath.Join(project.Path, jiri.ProjectMetaDir, jiri.ProjectConfigFile)
	return lc.ToFile(jirix, configFile)
}

// Hook represents a hook to run
type Hook struct {
	Name        string   `xml:"name,attr"`
	Action      string   `xml:"action,attr"`
	ProjectName string   `xml:"project,attr"`
	XMLName     struct{} `xml:"hook"`
	ActionPath  string   `xml:"-"`
}

// HookKey is a unique string for a project.
type HookKey string

type Hooks map[HookKey]Hook

// Key returns the unique HookKey for the hook.
func (h Hook) Key() HookKey {
	return MakeHookKey(h.Name, h.ProjectName)
}

// MakeHookKey returns the hook key, given the hook and project name.
func MakeHookKey(name, projectName string) HookKey {
	return HookKey(name + KeySeparator + projectName)
}

func (h *Hook) validate() error {
	if strings.Contains(h.Name, KeySeparator) {
		return fmt.Errorf("bad hook: name cannot contain %q: %+v", KeySeparator, *h)
	}
	if strings.Contains(h.ProjectName, KeySeparator) {
		return fmt.Errorf("bad hook: project cannot contain %q: %+v", KeySeparator, *h)
	}
	return nil
}

// HooksByName implements the Sort interface. It sorts Hooks by the Name
// and ProjectName field.
type HooksByName []Hook

func (hooks HooksByName) Len() int {
	return len(hooks)
}
func (hooks HooksByName) Swap(i, j int) {
	hooks[i], hooks[j] = hooks[j], hooks[i]
}
func (hooks HooksByName) Less(i, j int) bool {
	if hooks[i].Name == hooks[j].Name {
		return hooks[i].ProjectName < hooks[j].ProjectName
	}
	return hooks[i].Name < hooks[j].Name
}

// LoadManifest loads the manifest, starting with the .jiri_manifest file,
// resolving remote and local imports.  Returns the projects specified by
// the manifest.
//
// WARNING: LoadManifest cannot be run multiple times in parallel!  It invokes
// git operations which require a lock on the filesystem.  If you see errors
// about ".git/index.lock exists", you are likely calling LoadManifest in
// parallel.
func LoadManifest(jirix *jiri.X) (Projects, Hooks, error) {
	jirix.TimerPush("load manifest")
	defer jirix.TimerPop()
	file := jirix.JiriManifestFile()
	localProjects, err := LocalProjects(jirix, FastScan)
	if err != nil {
		return nil, nil, err
	}
	return LoadManifestFile(jirix, file, localProjects, false)
}

// LoadManifestFile loads the manifest starting with the given file, resolving
// remote and local imports.  Local projects are used to resolve remote imports;
// if nil, encountering any remote import will result in an error.
//
// WARNING: LoadManifestFile cannot be run multiple times in parallel!  It
// invokes git operations which require a lock on the filesystem.  If you see
// errors about ".git/index.lock exists", you are likely calling
// LoadManifestFile in parallel.
func LoadManifestFile(jirix *jiri.X, file string, localProjects Projects, localManifest bool) (Projects, Hooks, error) {
	ld := newManifestLoader(localProjects, false, file)
	if err := ld.Load(jirix, "", "", file, "", "", "", localManifest); err != nil {
		return nil, nil, err
	}
	jirix.AddCleanupFunc(ld.cleanup)
	return ld.Projects, ld.Hooks, nil
}

func LoadUpdatedManifest(jirix *jiri.X, localProjects Projects, localManifest bool) (Projects, Hooks, error) {
	jirix.TimerPush("load updated manifest")
	defer jirix.TimerPop()
	ld := newManifestLoader(localProjects, true, jirix.JiriManifestFile())
	if err := ld.Load(jirix, "", "", jirix.JiriManifestFile(), "", "", "", localManifest); err != nil {
		return nil, nil, err
	}
	jirix.AddCleanupFunc(ld.cleanup)
	return ld.Projects, ld.Hooks, nil
}

// RunHooks runs all given hooks.
func RunHooks(jirix *jiri.X, hooks Hooks, runHookTimeout uint) error {
	jirix.TimerPush("run hooks")
	defer jirix.TimerPop()
	type result struct {
		outFile *os.File
		errFile *os.File
		err     error
	}
	ch := make(chan result)
	tmpDir, err := ioutil.TempDir("", "run-hooks")
	if err != nil {
		return fmt.Errorf("not able to create tmp dir: %v", err)
	}
	defer os.RemoveAll(tmpDir)
	for _, hook := range hooks {
		go func(hook Hook) {
			logStr := fmt.Sprintf("running hook(%s) for project %q", hook.Name, hook.ProjectName)
			jirix.Logger.Debugf(logStr)
			task := jirix.Logger.AddTaskMsg(logStr)
			defer task.Done()
			outFile, err := ioutil.TempFile(tmpDir, hook.Name+"-out")
			if err != nil {
				ch <- result{nil, nil, fmtError(err)}
				return
			}
			errFile, err := ioutil.TempFile(tmpDir, hook.Name+"-err")
			if err != nil {
				ch <- result{nil, nil, fmtError(err)}
				return
			}

			fmt.Fprintf(outFile, "output for hook(%v) for project %q\n", hook.Name, hook.ProjectName)
			fmt.Fprintf(errFile, "Error for hook(%v) for project %q\n", hook.Name, hook.ProjectName)
			cmdLine := filepath.Join(hook.ActionPath, hook.Action)
			err = retry.Function(jirix, func() error {
				ctx, cancel := context.WithTimeout(context.Background(), time.Duration(runHookTimeout)*time.Minute)
				defer cancel()
				command := exec.CommandContext(ctx, cmdLine)
				command.Dir = hook.ActionPath
				command.Stdin = os.Stdin
				command.Stdout = outFile
				command.Stderr = errFile
				env := jirix.Env()
				command.Env = envvar.MapToSlice(env)
				jirix.Logger.Tracef("Run: %q", cmdLine)
				err = command.Run()
				if ctx.Err() == context.DeadlineExceeded {
					err = ctx.Err()
				}
				return err
			}, fmt.Sprintf("running hook(%s) for project %s", hook.Name, hook.ProjectName),
				retry.AttemptsOpt(jirix.Attempts))
			ch <- result{outFile, errFile, err}
		}(hook)

	}

	err = nil
	timeout := false
	for range hooks {
		out := <-ch
		defer func() {
			if out.outFile != nil {
				out.outFile.Close()
			}
			if out.errFile != nil {
				out.errFile.Close()
			}
		}()
		if out.err == context.DeadlineExceeded {
			timeout = true
			out.outFile.Sync()
			out.outFile.Seek(0, 0)
			var buf bytes.Buffer
			io.Copy(&buf, out.outFile)
			jirix.Logger.Errorf("Timeout while executing hook\n%s\n\n", buf.String())
			err = fmt.Errorf("Hooks execution failed.")
			continue
		}
		var outBuf bytes.Buffer
		if out.outFile != nil {
			out.outFile.Sync()
			out.outFile.Seek(0, 0)
			io.Copy(&outBuf, out.outFile)
		}
		if out.err != nil {
			var buf bytes.Buffer
			if out.errFile != nil {
				out.errFile.Sync()
				out.errFile.Seek(0, 0)
				io.Copy(&buf, out.errFile)
			}
			jirix.Logger.Errorf("%s\n%s\n%s\n", out.err, buf.String(), outBuf.String())
			err = fmt.Errorf("Hooks execution failed.")
		} else {
			if outBuf.String() != "" {
				jirix.Logger.Debugf("%s\n", outBuf.String())
			}
		}
	}
	if timeout {
		err = fmt.Errorf("%s Use %s flag to set timeout.", err, jirix.Color.Yellow("-hook-timeout"))
	}
	return err
}

func applyGitHooks(jirix *jiri.X, ops []operation) error {
	jirix.TimerPush("apply githooks")
	defer jirix.TimerPop()
	commitHookMap := make(map[string][]byte)
	for _, op := range ops {
		if op.Kind() != "delete" && !op.Project().LocalConfig.Ignore && !op.Project().LocalConfig.NoUpdate {
			if op.Project().GerritHost != "" {
				hookPath := filepath.Join(op.Project().Path, ".git", "hooks", "commit-msg")
				commitHook, err := os.Create(hookPath)
				if err != nil {
					return fmtError(err)
				}
				bytes, ok := commitHookMap[op.Project().GerritHost]
				if !ok {
					downloadPath := op.Project().GerritHost + "/tools/hooks/commit-msg"
					response, err := http.Get(downloadPath)
					if err != nil {
						return fmt.Errorf("Error while downloading %q: %v", downloadPath, err)
					}
					if response.StatusCode != http.StatusOK {
						return fmt.Errorf("Error while downloading %q, status code: %d", downloadPath, response.StatusCode)
					}
					defer response.Body.Close()
					if b, err := ioutil.ReadAll(response.Body); err != nil {
						return fmt.Errorf("Error while downloading %q: %v", downloadPath, err)
					} else {
						bytes = b
						commitHookMap[op.Project().GerritHost] = b
					}
				}
				if _, err := commitHook.Write(bytes); err != nil {
					return err
				}
				commitHook.Close()
				if err := os.Chmod(hookPath, 0750); err != nil {
					return fmtError(err)
				}
			}
			hookPath := filepath.Join(op.Project().Path, ".git", "hooks", "post-commit")
			commitHook, err := os.Create(hookPath)
			if err != nil {
				return err
			}
			bytes := []byte(`#!/bin/sh

if ! git symbolic-ref HEAD &> /dev/null; then
  echo -e "WARNING: You are in a detached head state! You might lose this commit.\nUse 'git checkout -b <branch> to put it on a branch.\n"
fi
`)
			if _, err := commitHook.Write(bytes); err != nil {
				return err
			}
			commitHook.Close()
			if err := os.Chmod(hookPath, 0750); err != nil {
				return err
			}
		}
		if op.Project().GitHooks == "" {
			continue
		}
		// Don't want to run hooks when repo is deleted
		if op.Kind() == "delete" {
			continue
		}
		// Apply git hooks, overwriting any existing hooks.  Jiri is in control of
		// writing all hooks.
		gitHooksDstDir := filepath.Join(op.Project().Path, ".git", "hooks")
		// Copy the specified GitHooks directory into the project's git
		// hook directory.  We walk the file system, creating directories
		// and copying files as we encounter them.
		copyFn := func(path string, info os.FileInfo, err error) error {
			if err != nil {
				return err
			}
			relPath, err := filepath.Rel(op.Project().GitHooks, path)
			if err != nil {
				return err
			}
			dst := filepath.Join(gitHooksDstDir, relPath)
			if info.IsDir() {
				return fmtError(os.MkdirAll(dst, 0755))
			}
			src, err := ioutil.ReadFile(path)
			if err != nil {
				return fmtError(err)
			}
			// The file *must* be executable to be picked up by git.
			return fmtError(ioutil.WriteFile(dst, src, 0755))
		}
		if err := filepath.Walk(op.Project().GitHooks, copyFn); err != nil {
			return err
		}
	}
	return nil
}