package accounting

import (
	"bytes"
	"fmt"
	"strings"
	"sync"
	"time"

	"github.com/ncw/rclone/fs"
	"github.com/ncw/rclone/fs/rc"
)

var (
	// Stats is global statistics counter
	Stats = NewStats()
)

func init() {
	// Set the function pointer up in fs
	fs.CountError = Stats.Error

	rc.Add(rc.Call{
		Path:  "core/stats",
		Fn:    Stats.RemoteStats,
		Title: "Returns stats about current transfers.",
		Help: `
This returns all available stats

	rclone rc core/stats

Returns the following values:

` + "```" + `
{
	"speed": average speed in bytes/sec since start of the process,
	"bytes": total transferred bytes since the start of the process,
	"errors": number of errors,
	"checks": number of checked files,
	"transfers": number of transferred files,
	"deletes" : number of deleted files,
	"elapsedTime": time in seconds since the start of the process,
	"lastError": last occurred error,
	"transferring": an array of currently active file transfers:
		[
			{
				"bytes": total transferred bytes for this file,
				"eta": estimated time in seconds until file transfer completion
				"name": name of the file,
				"percentage": progress of the file transfer in percent,
				"speed": speed in bytes/sec,
				"speedAvg": speed in bytes/sec as an exponentially weighted moving average,
				"size": size of the file in bytes
			}
		],
	"checking": an array of names of currently active file checks
		[]
}
` + "```" + `
Values for "transferring", "checking" and "lastError" are only assigned if data is available.
The value for "eta" is null if an eta cannot be determined.
`,
	})
}

// StatsInfo accounts all transfers
type StatsInfo struct {
	mu           sync.RWMutex
	bytes        int64
	errors       int64
	lastError    error
	checks       int64
	checking     *stringSet
	transfers    int64
	transferring *stringSet
	deletes      int64
	start        time.Time
	inProgress   *inProgress
}

// NewStats cretates an initialised StatsInfo
func NewStats() *StatsInfo {
	return &StatsInfo{
		checking:     newStringSet(fs.Config.Checkers),
		transferring: newStringSet(fs.Config.Transfers),
		start:        time.Now(),
		inProgress:   newInProgress(),
	}
}

// RemoteStats returns stats for rc
func (s *StatsInfo) RemoteStats(in rc.Params) (out rc.Params, err error) {
	out = make(rc.Params)
	s.mu.RLock()
	dt := time.Now().Sub(s.start)
	dtSeconds := dt.Seconds()
	speed := 0.0
	if dt > 0 {
		speed = float64(s.bytes) / dtSeconds
	}
	out["speed"] = speed
	out["bytes"] = s.bytes
	out["errors"] = s.errors
	out["checks"] = s.checks
	out["transfers"] = s.transfers
	out["deletes"] = s.deletes
	out["elapsedTime"] = dtSeconds
	s.mu.RUnlock()
	if !s.checking.empty() {
		var c []string
		s.checking.mu.RLock()
		defer s.checking.mu.RUnlock()
		for name := range s.checking.items {
			c = append(c, name)
		}
		out["checking"] = c
	}
	if !s.transferring.empty() {
		var t []interface{}
		s.transferring.mu.RLock()
		defer s.transferring.mu.RUnlock()
		for name := range s.transferring.items {
			if acc := s.inProgress.get(name); acc != nil {
				t = append(t, acc.RemoteStats())
			} else {
				t = append(t, name)
			}
		}
		out["transferring"] = t
	}
	if s.errors > 0 {
		out["lastError"] = s.lastError
	}
	return out, nil
}

// String convert the StatsInfo to a string for printing
func (s *StatsInfo) String() string {
	s.mu.RLock()

	dt := time.Now().Sub(s.start)
	dtSeconds := dt.Seconds()
	speed := 0.0
	if dt > 0 {
		speed = float64(s.bytes) / dtSeconds
	}
	dtRounded := dt - (dt % (time.Second / 10))
	buf := &bytes.Buffer{}

	if fs.Config.DataRateUnit == "bits" {
		speed = speed * 8
	}

	_, _ = fmt.Fprintf(buf, `
Transferred:   %10s (%s)
Errors:        %10d
Checks:        %10d
Transferred:   %10d
Elapsed time:  %10v
`,
		fs.SizeSuffix(s.bytes).Unit("Bytes"), fs.SizeSuffix(speed).Unit(strings.Title(fs.Config.DataRateUnit)+"/s"),
		s.errors,
		s.checks,
		s.transfers,
		dtRounded)

	// checking and transferring have their own locking so unlock
	// here to prevent deadlock on GetBytes
	s.mu.RUnlock()

	if !s.checking.empty() {
		_, _ = fmt.Fprintf(buf, "Checking:\n%s\n", s.checking)
	}
	if !s.transferring.empty() {
		_, _ = fmt.Fprintf(buf, "Transferring:\n%s\n", s.transferring)
	}
	return buf.String()
}

// Log outputs the StatsInfo to the log
func (s *StatsInfo) Log() {
	fs.LogLevelPrintf(fs.Config.StatsLogLevel, nil, "%v\n", s)
}

// Bytes updates the stats for bytes bytes
func (s *StatsInfo) Bytes(bytes int64) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.bytes += bytes
}

// GetBytes returns the number of bytes transferred so far
func (s *StatsInfo) GetBytes() int64 {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.bytes
}

// Errors updates the stats for errors
func (s *StatsInfo) Errors(errors int64) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.errors += errors
}

// GetErrors reads the number of errors
func (s *StatsInfo) GetErrors() int64 {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.errors
}

// GetLastError returns the lastError
func (s *StatsInfo) GetLastError() error {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.lastError
}

// Deletes updates the stats for deletes
func (s *StatsInfo) Deletes(deletes int64) int64 {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.deletes += deletes
	return s.deletes
}

// ResetCounters sets the counters (bytes, checks, errors, transfers) to 0
func (s *StatsInfo) ResetCounters() {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.bytes = 0
	s.errors = 0
	s.checks = 0
	s.transfers = 0
	s.deletes = 0
}

// ResetErrors sets the errors count to 0
func (s *StatsInfo) ResetErrors() {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.errors = 0
}

// Errored returns whether there have been any errors
func (s *StatsInfo) Errored() bool {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.errors != 0
}

// Error adds a single error into the stats and assigns lastError
func (s *StatsInfo) Error(err error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.errors++
	s.lastError = err
}

// Checking adds a check into the stats
func (s *StatsInfo) Checking(remote string) {
	s.checking.add(remote)
}

// DoneChecking removes a check from the stats
func (s *StatsInfo) DoneChecking(remote string) {
	s.checking.del(remote)
	s.mu.Lock()
	s.checks++
	s.mu.Unlock()
}

// GetTransfers reads the number of transfers
func (s *StatsInfo) GetTransfers() int64 {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.transfers
}

// Transferring adds a transfer into the stats
func (s *StatsInfo) Transferring(remote string) {
	s.transferring.add(remote)
}

// DoneTransferring removes a transfer from the stats
//
// if ok is true then it increments the transfers count
func (s *StatsInfo) DoneTransferring(remote string, ok bool) {
	s.transferring.del(remote)
	if ok {
		s.mu.Lock()
		s.transfers++
		s.mu.Unlock()
	}
}