package main

import (
	"context"
	"fmt"
	"strconv"
	"unsafe"

	"yvbolt/lexer"

	"github.com/redis/go-redis/v9"
	"github.com/ying32/govcl/vcl"
)

type redisLoadedDatabase struct {
	displayName string
	db          *redis.Client
	nav         *vcl.TTreeNode

	currentDb     int
	maxDb         int
	serverVersion string // populated at connection-time from INFO command

	arena []*navData // keepalive
}

func (ld *redisLoadedDatabase) DisplayName() string {
	return ld.displayName
}

func (ld *redisLoadedDatabase) DriverName() string {
	return "Redis " + ld.serverVersion
}

func (ld *redisLoadedDatabase) RootElement() *vcl.TTreeNode {
	return ld.nav
}

func (ld *redisLoadedDatabase) Keepalive(ndata *navData) {
	ld.arena = append(ld.arena, ndata)
}

func (ld *redisLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) {
	ctx := context.Background()

	if len(ndata.bucketPath) == 0 {
		// Top-level: Show info() on main Properties tab
		infostr, err := ld.db.Info(ctx).Result()
		if err != nil {
			vcl.ShowMessage(fmt.Sprintf("Retreiving database info: %v", err))
			return
		}

		f.propertiesBox.SetText(infostr)

		// Leave data tab disabled (default behaviour)

	} else if len(ndata.bucketPath) == 1 {
		// One selected database
		// Figure out its content
		err := ld.db.Do(ctx, "SELECT", ndata.bucketPath[0]).Err()
		if err != nil {
			vcl.ShowMessage(fmt.Sprintf("Switching to database %q: %v", ndata.bucketPath[0], err))
			return
		}

		allKeys, err := ld.db.Keys(ctx, "*").Result()
		if err != nil {
			vcl.ShowMessage(fmt.Sprintf("Listing keys in database %q: %v", ndata.bucketPath[0], err))
			return
		}

		f.propertiesBox.SetText(fmt.Sprintf("Database %s\nTotal keys: %d\n", ndata.bucketPath[0], len(allKeys)))

		// Redis always uses Key + Value as the columns

		colKey := f.contentBox.Columns().Add()
		colKey.Title().SetCaption("Key")
		colType := f.contentBox.Columns().Add()
		colType.Title().SetCaption("Type")
		colVal := f.contentBox.Columns().Add()
		colVal.Title().SetCaption("Value")

		for _, key := range allKeys {
			typeName, err := ld.db.Type(ctx, key).Result()
			if err != nil {
				vcl.ShowMessage(fmt.Sprintf("Loading %q/%q: %v", ndata.bucketPath[0], key, err))
				return
			}

			rpos := f.contentBox.RowCount()
			f.contentBox.SetRowCount(rpos + 1)
			f.contentBox.SetCells(0, rpos, formatUtf8([]byte(key)))
			f.contentBox.SetCells(1, rpos, typeName)

			switch typeName {
			case "string":
				val, err := ld.db.Get(ctx, key).Result()
				if err != nil {
					vcl.ShowMessage(fmt.Sprintf("Loading %q/%q: %v", ndata.bucketPath[0], key, err))
					return
				}
				f.contentBox.SetCells(2, rpos, val)

			case "hash":
				val, err := ld.db.HGetAll(ctx, key).Result()
				if err != nil {
					vcl.ShowMessage(fmt.Sprintf("Loading %q/%q: %v", ndata.bucketPath[0], key, err))
					return
				}
				// It's a map[string]string
				f.contentBox.SetCells(2, rpos, formatAny(val))

			case "lists":
				fallthrough
			case "sets":
				fallthrough
			case "sorted sets":
				fallthrough
			case "stream":
				fallthrough

			default:
				f.contentBox.SetCells(2, rpos, "<<<other object type>>>")
			}

		}

		// Valid
		vcl_stringgrid_columnwidths(f.contentBox)
		f.contentBox.SetEnabled(true)

	} else {
		vcl.ShowMessage(fmt.Sprintf("Unexpected nav position %q", ndata.bucketPath))
		return

	}
}

func (n *redisLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
	return ErrNotSupported
}

func (ld *redisLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
	// ctx := context.Background()

	if len(ndata.bucketPath) == 0 {
		// Top-level: list of all child databases (usually 16x)
		ret := make([]string, 0, ld.maxDb)
		for i := 0; i < ld.maxDb; i++ {
			ret = append(ret, fmt.Sprintf("%d", i))
		}
		return ret, nil

	} else if len(ndata.bucketPath) == 1 {
		// One selected database
		// No child keys underneath it
		return []string{}, nil

	} else {
		return nil, fmt.Errorf("Unexpected nav position %q", ndata.bucketPath)

	}
}

func (ld *redisLoadedDatabase) NavContext(ndata *navData) ([]contextAction, error) {
	return nil, nil // No special actions are supported
}

func (ld *redisLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
	ctx := context.Background()

	// Need to parse the query into separate string+args fields for the protocol
	fields, err := lexer.Fields(query)
	if err != nil {
		return fmt.Errorf("Parsing the query: %w", err)
	}

	fields_boxed := box_interface(fields)

	ret, err := ld.db.Do(ctx, fields_boxed...).Result()
	if err != nil {
		return fmt.Errorf("The redis query returned an error: %w", err)
	}

	vcl_stringgrid_clear(resultArea)

	colVal := resultArea.Columns().Add()
	colVal.Title().SetCaption("Result")

	// The result is probably a single value or a string slice
	switch ret := ret.(type) {
	case []string:
		// Multiple values
		for _, single := range ret {

			rpos := resultArea.RowCount()
			resultArea.SetRowCount(rpos + 1)
			resultArea.SetCells(0, rpos, formatUtf8([]byte(single)))
		}

	default:
		// Single value
		rpos := resultArea.RowCount()
		resultArea.SetRowCount(rpos + 1)
		resultArea.SetCells(0, rpos, formatAny(ret)) // formatUtf8

	}

	vcl_stringgrid_columnwidths(resultArea)
	resultArea.SetEnabled(true)

	return nil
}

func (ld *redisLoadedDatabase) Close() {
	_ = ld.db.Close()
	ld.arena = nil
}

var _ loadedDatabase = &redisLoadedDatabase{} // interface assertion

//

func (f *TMainForm) redisConnect(opts *redis.Options) {
	// TODO load in background thread to stop blocking the UI
	ctx := context.Background()

	ld := &redisLoadedDatabase{
		displayName:   opts.Addr,
		currentDb:     0,
		maxDb:         1,
		serverVersion: "<unknown>",
	}

	// Patch in a hook to remember current DB after keepalive reconnection
	opts.DB = 0 // Default
	opts.OnConnect = func(ctx context.Context, cn *redis.Conn) error {
		return cn.Select(ctx, ld.currentDb).Err()
	}

	// NewClient doesn't necessarily connect, so it can't throw an err
	ld.db = redis.NewClient(opts)

	// Make an INFO request (mandatory)
	info, err := ld.db.InfoMap(ctx).Result()
	if err != nil {
		vcl.ShowMessage(fmt.Sprintf("Failed to connect to Redis server: During INFO: %v", err))
		return
	}

	if serverInfo, ok := info["Server"]; ok {
		if v, ok := serverInfo["redis_version"]; ok {
			ld.serverVersion = v
		}
	}

	// List available databases (usually 1..16) with "0" as default
	// If this fails, probably the target redis does not support multiple databases
	// (e.g. Redis Cluster). Assume max=0.
	if maxDatabases, err := ld.db.ConfigGet(ctx, "databases").Result(); err == nil {
		// Got a result. Must parse it
		m, err := strconv.ParseInt(maxDatabases["databases"], 10, 64)
		if err != nil {
			vcl.ShowMessage(fmt.Sprintf("Failed to connect to Redis server: During CONFIG GET databases: %v", err))
			return
		}

		ld.maxDb = int(m)
	}

	// Done with setup

	ld.nav = f.Buckets.Items().Add(nil, ld.displayName)
	ld.nav.SetHasChildren(true) // dynamically populate in OnNavExpanding
	ld.nav.SetImageIndex(imgDatabase)
	ld.nav.SetSelectedIndex(imgDatabase)
	navData := &navData{
		ld:             ld,
		childrenLoaded: false,      // will be loaded dynamically
		bucketPath:     []string{}, // empty = root
	}
	ld.nav.SetData(unsafe.Pointer(navData))

	f.dbs = append(f.dbs, ld)
	f.Buckets.SetSelected(ld.nav) // Select new element

	ld.Keepalive(navData)
}