package redis

import (
	"fmt"
	"log"
	"os"
	"time"

	"github.com/go-redis/redis/internal"
	"github.com/go-redis/redis/internal/pool"
	"github.com/go-redis/redis/internal/proto"
)

// Redis nil reply, .e.g. when key does not exist.
const Nil = internal.Nil

func init() {
	SetLogger(log.New(os.Stderr, "redis: ", log.LstdFlags|log.Lshortfile))
}

func SetLogger(logger *log.Logger) {
	internal.Logger = logger
}

func (c *baseClient) String() string {
	return fmt.Sprintf("Redis<%s db:%d>", c.getAddr(), c.opt.DB)
}

func (c *baseClient) newConn() (*pool.Conn, error) {
	cn, err := c.connPool.NewConn()
	if err != nil {
		return nil, err
	}

	if !cn.Inited {
		if err := c.initConn(cn); err != nil {
			_ = c.connPool.CloseConn(cn)
			return nil, err
		}
	}

	return cn, nil
}

func (c *baseClient) getConn() (*pool.Conn, bool, error) {
	cn, isNew, err := c.connPool.Get()
	if err != nil {
		return nil, false, err
	}

	if !cn.Inited {
		if err := c.initConn(cn); err != nil {
			_ = c.connPool.Remove(cn)
			return nil, false, err
		}
	}

	return cn, isNew, nil
}

func (c *baseClient) releaseConn(cn *pool.Conn, err error) bool {
	if internal.IsBadConn(err, false) {
		_ = c.connPool.Remove(cn)
		return false
	}

	_ = c.connPool.Put(cn)
	return true
}

func (c *baseClient) initConn(cn *pool.Conn) error {
	cn.Inited = true

	if c.opt.Password == "" &&
		c.opt.DB == 0 &&
		!c.opt.readOnly &&
		c.opt.OnConnect == nil {
		return nil
	}

	// Temp client to initialize connection.
	conn := &Conn{
		baseClient: baseClient{
			opt:      c.opt,
			connPool: pool.NewSingleConnPool(cn),
		},
	}
	conn.setProcessor(conn.Process)

	_, err := conn.Pipelined(func(pipe Pipeliner) error {
		if c.opt.Password != "" {
			pipe.Auth(c.opt.Password)
		}

		if c.opt.DB > 0 {
			pipe.Select(c.opt.DB)
		}

		if c.opt.readOnly {
			pipe.ReadOnly()
		}

		return nil
	})
	if err != nil {
		return err
	}

	if c.opt.OnConnect != nil {
		return c.opt.OnConnect(conn)
	}
	return nil
}

// WrapProcess replaces the process func. It takes a function createWrapper
// which is supplied by the user. createWrapper takes the old process func as
// an input and returns the new wrapper process func. createWrapper should
// use call the old process func within the new process func.
func (c *baseClient) WrapProcess(fn func(oldProcess func(cmd Cmder) error) func(cmd Cmder) error) {
	c.process = fn(c.defaultProcess)
}

func (c *baseClient) Process(cmd Cmder) error {
	if c.process != nil {
		return c.process(cmd)
	}
	return c.defaultProcess(cmd)
}

func (c *baseClient) defaultProcess(cmd Cmder) error {
	for attempt := 0; attempt <= c.opt.MaxRetries; attempt++ {
		if attempt > 0 {
			time.Sleep(c.retryBackoff(attempt))
		}

		cn, _, err := c.getConn()
		if err != nil {
			cmd.setErr(err)
			if internal.IsRetryableError(err) {
				continue
			}
			return err
		}

		cn.SetWriteTimeout(c.opt.WriteTimeout)
		if err := writeCmd(cn, cmd); err != nil {
			c.releaseConn(cn, err)
			cmd.setErr(err)
			if internal.IsRetryableError(err) {
				continue
			}
			return err
		}

		cn.SetReadTimeout(c.cmdTimeout(cmd))
		err = cmd.readReply(cn)
		c.releaseConn(cn, err)
		if err != nil && internal.IsRetryableError(err) {
			continue
		}

		return err
	}

	return cmd.Err()
}

func (c *baseClient) retryBackoff(attempt int) time.Duration {
	return internal.RetryBackoff(attempt, c.opt.MinRetryBackoff, c.opt.MaxRetryBackoff)
}

func (c *baseClient) cmdTimeout(cmd Cmder) time.Duration {
	if timeout := cmd.readTimeout(); timeout != nil {
		return *timeout
	} else {
		return c.opt.ReadTimeout
	}
}

// Close closes the client, releasing any open resources.
//
// It is rare to Close a Client, as the Client is meant to be
// long-lived and shared between many goroutines.
func (c *baseClient) Close() error {
	var firstErr error
	if c.onClose != nil {
		if err := c.onClose(); err != nil && firstErr == nil {
			firstErr = err
		}
	}
	if err := c.connPool.Close(); err != nil && firstErr == nil {
		firstErr = err
	}
	return firstErr
}

func (c *baseClient) getAddr() string {
	return c.opt.Addr
}

type pipelineProcessor func(*pool.Conn, []Cmder) (bool, error)

func (c *baseClient) pipelineExecer(p pipelineProcessor) pipelineExecer {
	return func(cmds []Cmder) error {
		for attempt := 0; attempt <= c.opt.MaxRetries; attempt++ {
			if attempt > 0 {
				time.Sleep(c.retryBackoff(attempt))
			}

			cn, _, err := c.getConn()
			if err != nil {
				setCmdsErr(cmds, err)
				return err
			}

			canRetry, err := p(cn, cmds)

			if err == nil || internal.IsRedisError(err) {
				_ = c.connPool.Put(cn)
				break
			}
			_ = c.connPool.Remove(cn)

			if !canRetry || !internal.IsRetryableError(err) {
				break
			}
		}
		return firstCmdsErr(cmds)
	}
}

func (c *baseClient) pipelineProcessCmds(cn *pool.Conn, cmds []Cmder) (bool, error) {
	cn.SetWriteTimeout(c.opt.WriteTimeout)
	if err := writeCmd(cn, cmds...); err != nil {
		setCmdsErr(cmds, err)
		return true, err
	}

	// Set read timeout for all commands.
	cn.SetReadTimeout(c.opt.ReadTimeout)
	return true, pipelineReadCmds(cn, cmds)
}

func pipelineReadCmds(cn *pool.Conn, cmds []Cmder) error {
	for _, cmd := range cmds {
		err := cmd.readReply(cn)
		if err != nil && !internal.IsRedisError(err) {
			return err
		}
	}
	return nil
}

func (c *baseClient) txPipelineProcessCmds(cn *pool.Conn, cmds []Cmder) (bool, error) {
	cn.SetWriteTimeout(c.opt.WriteTimeout)
	if err := txPipelineWriteMulti(cn, cmds); err != nil {
		setCmdsErr(cmds, err)
		return true, err
	}

	// Set read timeout for all commands.
	cn.SetReadTimeout(c.opt.ReadTimeout)

	if err := c.txPipelineReadQueued(cn, cmds); err != nil {
		setCmdsErr(cmds, err)
		return false, err
	}

	return false, pipelineReadCmds(cn, cmds)
}

func txPipelineWriteMulti(cn *pool.Conn, cmds []Cmder) error {
	multiExec := make([]Cmder, 0, len(cmds)+2)
	multiExec = append(multiExec, NewStatusCmd("MULTI"))
	multiExec = append(multiExec, cmds...)
	multiExec = append(multiExec, NewSliceCmd("EXEC"))
	return writeCmd(cn, multiExec...)
}

func (c *baseClient) txPipelineReadQueued(cn *pool.Conn, cmds []Cmder) error {
	// Parse queued replies.
	var statusCmd StatusCmd
	if err := statusCmd.readReply(cn); err != nil {
		return err
	}

	for _ = range cmds {
		err := statusCmd.readReply(cn)
		if err != nil && !internal.IsRedisError(err) {
			return err
		}
	}

	// Parse number of replies.
	line, err := cn.Rd.ReadLine()
	if err != nil {
		if err == Nil {
			err = TxFailedErr
		}
		return err
	}

	switch line[0] {
	case proto.ErrorReply:
		return proto.ParseErrorReply(line)
	case proto.ArrayReply:
		// ok
	default:
		err := fmt.Errorf("redis: expected '*', but got line %q", line)
		return err
	}

	return nil
}

//------------------------------------------------------------------------------

// Client is a Redis client representing a pool of zero or more
// underlying connections. It's safe for concurrent use by multiple
// goroutines.
type Client struct {
	baseClient
	cmdable
}

func newClient(opt *Options, pool pool.Pooler) *Client {
	client := Client{
		baseClient: baseClient{
			opt:      opt,
			connPool: pool,
		},
	}
	client.setProcessor(client.Process)
	return &client
}

// NewClient returns a client to the Redis Server specified by Options.
func NewClient(opt *Options) *Client {
	opt.init()
	return newClient(opt, newConnPool(opt))
}

func (c *Client) copy() *Client {
	c2 := new(Client)
	*c2 = *c
	c2.setProcessor(c2.Process)
	return c2
}

// Options returns read-only Options that were used to create the client.
func (c *Client) Options() *Options {
	return c.opt
}

// PoolStats returns connection pool stats.
func (c *Client) PoolStats() *PoolStats {
	s := c.connPool.Stats()
	return &PoolStats{
		Requests: s.Requests,
		Hits:     s.Hits,
		Timeouts: s.Timeouts,

		TotalConns: s.TotalConns,
		FreeConns:  s.FreeConns,
	}
}

func (c *Client) Pipelined(fn func(Pipeliner) error) ([]Cmder, error) {
	return c.Pipeline().pipelined(fn)
}

func (c *Client) Pipeline() Pipeliner {
	pipe := Pipeline{
		exec: c.pipelineExecer(c.pipelineProcessCmds),
	}
	pipe.setProcessor(pipe.Process)
	return &pipe
}

func (c *Client) TxPipelined(fn func(Pipeliner) error) ([]Cmder, error) {
	return c.TxPipeline().pipelined(fn)
}

// TxPipeline acts like Pipeline, but wraps queued commands with MULTI/EXEC.
func (c *Client) TxPipeline() Pipeliner {
	pipe := Pipeline{
		exec: c.pipelineExecer(c.txPipelineProcessCmds),
	}
	pipe.setProcessor(pipe.Process)
	return &pipe
}

func (c *Client) pubSub() *PubSub {
	return &PubSub{
		opt: c.opt,

		newConn: func(channels []string) (*pool.Conn, error) {
			return c.newConn()
		},
		closeConn: c.connPool.CloseConn,
	}
}

// Subscribe subscribes the client to the specified channels.
// Channels can be omitted to create empty subscription.
func (c *Client) Subscribe(channels ...string) *PubSub {
	pubsub := c.pubSub()
	if len(channels) > 0 {
		_ = pubsub.Subscribe(channels...)
	}
	return pubsub
}

// PSubscribe subscribes the client to the given patterns.
// Patterns can be omitted to create empty subscription.
func (c *Client) PSubscribe(channels ...string) *PubSub {
	pubsub := c.pubSub()
	if len(channels) > 0 {
		_ = pubsub.PSubscribe(channels...)
	}
	return pubsub
}

//------------------------------------------------------------------------------

// Conn is like Client, but its pool contains single connection.
type Conn struct {
	baseClient
	statefulCmdable
}

func (c *Conn) Pipelined(fn func(Pipeliner) error) ([]Cmder, error) {
	return c.Pipeline().pipelined(fn)
}

func (c *Conn) Pipeline() Pipeliner {
	pipe := Pipeline{
		exec: c.pipelineExecer(c.pipelineProcessCmds),
	}
	pipe.setProcessor(pipe.Process)
	return &pipe
}

func (c *Conn) TxPipelined(fn func(Pipeliner) error) ([]Cmder, error) {
	return c.TxPipeline().pipelined(fn)
}

// TxPipeline acts like Pipeline, but wraps queued commands with MULTI/EXEC.
func (c *Conn) TxPipeline() Pipeliner {
	pipe := Pipeline{
		exec: c.pipelineExecer(c.txPipelineProcessCmds),
	}
	pipe.setProcessor(pipe.Process)
	return &pipe
}