// Package config collects together all configuration settings
// NOTE: Subject to change, do not rely on this package from outside git-lfs source
package config

import (
	"errors"
	"fmt"
	"os"
	"reflect"
	"strconv"
	"strings"
	"sync"

	"github.com/ThomsonReutersEikon/go-ntlm/ntlm"
	"github.com/bgentry/go-netrc/netrc"
	"github.com/git-lfs/git-lfs/git"
	"github.com/git-lfs/git-lfs/tools"
	"github.com/rubyist/tracerx"
)

var (
	Config                 = New()
	ShowConfigWarnings     = false
	defaultRemote          = "origin"
	gitConfigWarningPrefix = "lfs."
)

// FetchPruneConfig collects together the config options that control fetching and pruning
type FetchPruneConfig struct {
	// The number of days prior to current date for which (local) refs other than HEAD
	// will be fetched with --recent (default 7, 0 = only fetch HEAD)
	FetchRecentRefsDays int `git:"lfs.fetchrecentrefsdays"`
	// Makes the FetchRecentRefsDays option apply to remote refs from fetch source as well (default true)
	FetchRecentRefsIncludeRemotes bool `git:"lfs.fetchrecentremoterefs"`
	// number of days prior to latest commit on a ref that we'll fetch previous
	// LFS changes too (default 0 = only fetch at ref)
	FetchRecentCommitsDays int `git:"lfs.fetchrecentcommitsdays"`
	// Whether to always fetch recent even without --recent
	FetchRecentAlways bool `git:"lfs.fetchrecentalways"`
	// Number of days added to FetchRecent*; data outside combined window will be
	// deleted when prune is run. (default 3)
	PruneOffsetDays int `git:"lfs.pruneoffsetdays"`
	// Always verify with remote before pruning
	PruneVerifyRemoteAlways bool `git:"lfs.pruneverifyremotealways"`
	// Name of remote to check for unpushed and verify checks
	PruneRemoteName string `git:"lfs.pruneremotetocheck"`
}

type Configuration struct {
	// Os provides a `*Environment` used to access to the system's
	// environment through os.Getenv. It is the point of entry for all
	// system environment configuration.
	Os Environment

	// Git provides a `*Environment` used to access to the various levels of
	// `.gitconfig`'s. It is the point of entry for all Git environment
	// configuration.
	Git Environment

	CurrentRemote   string
	NtlmSession     ntlm.ClientSession
	envVars         map[string]string
	envVarsMutex    sync.Mutex
	IsTracingHttp   bool
	IsDebuggingHttp bool
	IsLoggingStats  bool

	loading        sync.Mutex // guards initialization of gitConfig and remotes
	remotes        []string
	extensions     map[string]Extension
	manualEndpoint *Endpoint
	parsedNetrc    netrcfinder
	urlAliasesMap  map[string]string
	urlAliasMu     sync.Mutex
}

func New() *Configuration {
	c := &Configuration{
		Os:            EnvironmentOf(NewOsFetcher()),
		CurrentRemote: defaultRemote,
		envVars:       make(map[string]string),
	}

	c.Git = &gitEnvironment{config: c}
	c.IsTracingHttp = c.Os.Bool("GIT_CURL_VERBOSE", false)
	c.IsDebuggingHttp = c.Os.Bool("LFS_DEBUG_HTTP", false)
	c.IsLoggingStats = c.Os.Bool("GIT_LOG_STATS", false)
	return c
}

// Values is a convenience type used to call the NewFromValues function. It
// specifies `Git` and `Env` maps to use as mock values, instead of calling out
// to real `.gitconfig`s and the `os.Getenv` function.
type Values struct {
	// Git and Os are the stand-in maps used to provide values for their
	// respective environments.
	Git, Os map[string]string
}

// NewFrom returns a new `*config.Configuration` that reads both its Git
// and Enviornment-level values from the ones provided instead of the actual
// `.gitconfig` file or `os.Getenv`, respectively.
//
// This method should only be used during testing.
func NewFrom(v Values) *Configuration {
	return &Configuration{
		Os:  EnvironmentOf(mapFetcher(v.Os)),
		Git: EnvironmentOf(mapFetcher(v.Git)),

		envVars: make(map[string]string, 0),
	}
}

// Unmarshal unmarshals the *Configuration in context into all of `v`'s fields,
// according to the following rules:
//
// Values are marshaled according to the given key and environment, as follows:
//	type T struct {
//		Field string `git:"key"`
//		Other string `os:"key"`
//	}
//
// If an unknown environment is given, an error will be returned. If there is no
// method supporting conversion into a field's type, an error will be returned.
// If no value is associated with the given key and environment, the field will
// // only be modified if there is a config value present matching the given
// key. If the field is already set to a non-zero value of that field's type,
// then it will be left alone.
//
// Otherwise, the field will be set to the value of calling the
// appropriately-typed method on the specified environment.
func (c *Configuration) Unmarshal(v interface{}) error {
	into := reflect.ValueOf(v)
	if into.Kind() != reflect.Ptr {
		return fmt.Errorf("lfs/config: unable to parse non-pointer type of %T", v)
	}
	into = into.Elem()

	for i := 0; i < into.Type().NumField(); i++ {
		field := into.Field(i)
		sfield := into.Type().Field(i)

		key, env, err := c.parseTag(sfield.Tag)
		if err != nil {
			return err
		}

		if env == nil {
			continue
		}

		var val interface{}
		switch sfield.Type.Kind() {
		case reflect.String:
			var ok bool

			val, ok = env.Get(key)
			if !ok {
				val = field.String()
			}
		case reflect.Int:
			val = env.Int(key, int(field.Int()))
		case reflect.Bool:
			val = env.Bool(key, field.Bool())
		default:
			return fmt.Errorf(
				"lfs/config: unsupported target type for field %q: %v",
				sfield.Name, sfield.Type.String())
		}

		if val != nil {
			into.Field(i).Set(reflect.ValueOf(val))
		}
	}

	return nil
}

// parseTag returns the key, environment, and optional error assosciated with a
// given tag. It will return the XOR of either the `git` or `os` tag. That is to
// say, a field tagged with EITHER `git` OR `os` is valid, but pone tagged with
// both is not.
//
// If neither field was found, then a nil environment will be returned.
func (c *Configuration) parseTag(tag reflect.StructTag) (key string, env Environment, err error) {
	git, os := tag.Get("git"), tag.Get("os")

	if len(git) != 0 && len(os) != 0 {
		return "", nil, errors.New("lfs/config: ambiguous tags")
	}

	if len(git) != 0 {
		return git, c.Git, nil
	}
	if len(os) != 0 {
		return os, c.Os, nil
	}

	return
}

// GitRemoteUrl returns the git clone/push url for a given remote (blank if not found)
// the forpush argument is to cater for separate remote.name.pushurl settings
func (c *Configuration) GitRemoteUrl(remote string, forpush bool) string {
	if forpush {
		if u, ok := c.Git.Get("remote." + remote + ".pushurl"); ok {
			return u
		}
	}

	if u, ok := c.Git.Get("remote." + remote + ".url"); ok {
		return u
	}

	if err := git.ValidateRemote(remote); err == nil {
		return remote
	}

	return ""

}

// Manually set an Endpoint to use instead of deriving from Git config
func (c *Configuration) SetManualEndpoint(e Endpoint) {
	c.manualEndpoint = &e
}

func (c *Configuration) Endpoint(operation string) Endpoint {
	if c.manualEndpoint != nil {
		return *c.manualEndpoint
	}

	if operation == "upload" {
		if url, ok := c.Git.Get("lfs.pushurl"); ok {
			return NewEndpointWithConfig(url, c)
		}
	}

	if url, ok := c.Git.Get("lfs.url"); ok {
		return NewEndpointWithConfig(url, c)
	}

	if len(c.CurrentRemote) > 0 && c.CurrentRemote != defaultRemote {
		if endpoint := c.RemoteEndpoint(c.CurrentRemote, operation); len(endpoint.Url) > 0 {
			return endpoint
		}
	}

	return c.RemoteEndpoint(defaultRemote, operation)
}

func (c *Configuration) ConcurrentTransfers() int {
	if c.NtlmAccess("download") {
		return 1
	}

	uploads := 3

	if v, ok := c.Git.Get("lfs.concurrenttransfers"); ok {
		n, err := strconv.Atoi(v)
		if err == nil && n > 0 {
			uploads = n
		}
	}

	return uploads
}

// BasicTransfersOnly returns whether to only allow "basic" HTTP transfers.
// Default is false, including if the lfs.basictransfersonly is invalid
func (c *Configuration) BasicTransfersOnly() bool {
	return c.Git.Bool("lfs.basictransfersonly", false)
}

// TusTransfersAllowed returns whether to only use "tus.io" HTTP transfers.
// Default is false, including if the lfs.tustransfers is invalid
func (c *Configuration) TusTransfersAllowed() bool {
	return c.Git.Bool("lfs.tustransfers", false)
}

func (c *Configuration) BatchTransfer() bool {
	return c.Git.Bool("lfs.batch", true)
}

func (c *Configuration) NtlmAccess(operation string) bool {
	return c.Access(operation) == "ntlm"
}

// PrivateAccess will retrieve the access value and return true if
// the value is set to private. When a repo is marked as having private
// access, the http requests for the batch api will fetch the credentials
// before running, otherwise the request will run without credentials.
func (c *Configuration) PrivateAccess(operation string) bool {
	return c.Access(operation) != "none"
}

// Access returns the access auth type.
func (c *Configuration) Access(operation string) string {
	return c.EndpointAccess(c.Endpoint(operation))
}

// SetAccess will set the private access flag in .git/config.
func (c *Configuration) SetAccess(operation string, authType string) {
	c.SetEndpointAccess(c.Endpoint(operation), authType)
}

func (c *Configuration) FindNetrcHost(host string) (*netrc.Machine, error) {
	c.loading.Lock()
	defer c.loading.Unlock()
	if c.parsedNetrc == nil {
		n, err := c.parseNetrc()
		if err != nil {
			return nil, err
		}
		c.parsedNetrc = n
	}

	return c.parsedNetrc.FindMachine(host), nil
}

// Manually override the netrc config
func (c *Configuration) SetNetrc(n netrcfinder) {
	c.parsedNetrc = n
}

func (c *Configuration) EndpointAccess(e Endpoint) string {
	key := fmt.Sprintf("lfs.%s.access", e.Url)
	if v, ok := c.Git.Get(key); ok && len(v) > 0 {
		lower := strings.ToLower(v)
		if lower == "private" {
			return "basic"
		}
		return lower
	}
	return "none"
}

func (c *Configuration) SetEndpointAccess(e Endpoint, authType string) {
	c.loadGitConfig()

	tracerx.Printf("setting repository access to %s", authType)
	key := fmt.Sprintf("lfs.%s.access", e.Url)

	// Modify the config cache because it's checked again in this process
	// without being reloaded.
	switch authType {
	case "", "none":
		git.Config.UnsetLocalKey("", key)
		c.Git.del(key)
	default:
		git.Config.SetLocal("", key, authType)
		c.Git.set(key, authType)
	}
}

func (c *Configuration) FetchIncludePaths() []string {
	patterns, _ := c.Git.Get("lfs.fetchinclude")
	return tools.CleanPaths(patterns, ",")
}

func (c *Configuration) FetchExcludePaths() []string {
	patterns, _ := c.Git.Get("lfs.fetchexclude")
	return tools.CleanPaths(patterns, ",")
}

func (c *Configuration) RemoteEndpoint(remote, operation string) Endpoint {
	if len(remote) == 0 {
		remote = defaultRemote
	}

	// Support separate push URL if specified and pushing
	if operation == "upload" {
		if url, ok := c.Git.Get("remote." + remote + ".lfspushurl"); ok {
			return NewEndpointWithConfig(url, c)
		}
	}
	if url, ok := c.Git.Get("remote." + remote + ".lfsurl"); ok {
		return NewEndpointWithConfig(url, c)
	}

	// finally fall back on git remote url (also supports pushurl)
	if url := c.GitRemoteUrl(remote, operation == "upload"); url != "" {
		return NewEndpointFromCloneURLWithConfig(url, c)
	}

	return Endpoint{}
}

func (c *Configuration) Remotes() []string {
	c.loadGitConfig()

	return c.remotes
}

// GitProtocol returns the protocol for the LFS API when converting from a
// git:// remote url.
func (c *Configuration) GitProtocol() string {
	if value, ok := c.Git.Get("lfs.gitprotocol"); ok {
		return value
	}
	return "https"
}

func (c *Configuration) Extensions() map[string]Extension {
	c.loadGitConfig()

	return c.extensions
}

// SortedExtensions gets the list of extensions ordered by Priority
func (c *Configuration) SortedExtensions() ([]Extension, error) {
	return SortExtensions(c.Extensions())
}

func (c *Configuration) urlAliases() map[string]string {
	c.urlAliasMu.Lock()
	defer c.urlAliasMu.Unlock()

	if c.urlAliasesMap == nil {
		c.urlAliasesMap = make(map[string]string)
		prefix := "url."
		suffix := ".insteadof"
		for gitkey, gitval := range c.Git.All() {
			if strings.HasPrefix(gitkey, prefix) && strings.HasSuffix(gitkey, suffix) {
				if _, ok := c.urlAliasesMap[gitval]; ok {
					fmt.Fprintf(os.Stderr, "WARNING: Multiple 'url.*.insteadof' keys with the same alias: %q\n", gitval)
				}
				c.urlAliasesMap[gitval] = gitkey[len(prefix) : len(gitkey)-len(suffix)]
			}
		}
	}

	return c.urlAliasesMap
}

// ReplaceUrlAlias returns a url with a prefix from a `url.*.insteadof` git
// config setting. If multiple aliases match, use the longest one.
// See https://git-scm.com/docs/git-config for Git's docs.
func (c *Configuration) ReplaceUrlAlias(rawurl string) string {
	var longestalias string
	aliases := c.urlAliases()
	for alias, _ := range aliases {
		if !strings.HasPrefix(rawurl, alias) {
			continue
		}

		if longestalias < alias {
			longestalias = alias
		}
	}

	if len(longestalias) > 0 {
		return aliases[longestalias] + rawurl[len(longestalias):]
	}

	return rawurl
}

func (c *Configuration) FetchPruneConfig() FetchPruneConfig {
	f := &FetchPruneConfig{
		FetchRecentRefsDays:           7,
		FetchRecentRefsIncludeRemotes: true,
		PruneOffsetDays:               3,
		PruneRemoteName:               "origin",
	}

	if err := c.Unmarshal(f); err != nil {
		panic(err.Error())
	}
	return *f
}

func (c *Configuration) SkipDownloadErrors() bool {
	return c.Os.Bool("GIT_LFS_SKIP_DOWNLOAD_ERRORS", false) || c.Git.Bool("lfs.skipdownloaderrors", false)
}

// loadGitConfig is a temporary measure to support legacy behavior dependent on
// accessing properties set by ReadGitConfig, namely:
//  - `c.extensions`
//  - `c.uniqRemotes`
//  - `c.gitConfig`
//
// Since the *gitEnvironment is responsible for setting these values on the
// (*config.Configuration) instance, we must call that method, if it exists.
//
// loadGitConfig returns a bool returning whether or not `loadGitConfig` was
// called AND the method did not return early.
func (c *Configuration) loadGitConfig() bool {
	if g, ok := c.Git.(*gitEnvironment); ok {
		return g.loadGitConfig()
	}

	return false
}

// CurrentCommitter returns the name/email that would be used to author a commit
// with this configuration. In particular, the "user.name" and "user.email"
// configuration values are used
func (c *Configuration) CurrentCommitter() (name, email string) {
	name, _ = c.Git.Get("user.name")
	email, _ = c.Git.Get("user.email")
	return
}