package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"git.gammaspectra.live/P2Pool/consensus/v3/p2pool/sidechain"
	"git.gammaspectra.live/P2Pool/consensus/v3/types"
	"git.gammaspectra.live/P2Pool/observer-cmd-utils/index"
	"git.gammaspectra.live/P2Pool/observer-cmd-utils/utils"
	"io"
	"log"
	"net/url"
	"nhooyr.io/websocket"
	"slices"
	"sync"
	"sync/atomic"
	"time"
)

type channelEntry struct {
	ApiEndpoint    string
	Channel        string
	Name           string
	PreviousBlocks foundBlocks
	PoolInfo       map[string]any
	Consensus      *sidechain.Consensus
	Tip            *index.SideBlock
	Window         map[types.Hash]*index.SideBlock
	ChainLock      sync.RWMutex

	Ws atomic.Pointer[websocket.Conn]
}

func (c *channelEntry) DesiredPruneDistance() uint64 {
	//prune after a whole day
	/*pruneDistance := (3600 * 24) / c.Consensus.TargetBlockTime
	if pruneDistance < c.Consensus.ChainWindowSize {
		pruneDistance = c.Consensus.ChainWindowSize
	}*/

	return c.Consensus.ChainWindowSize
}

func (c *channelEntry) SideBlockUnclesByTemplateId(id types.Hash) index.QueryIterator[index.SideBlock] {
	var uncles []index.SideBlockUncleEntry

	if b := c.SideBlockByTemplateId(id); b != nil && !b.IsUncle() {
		uncles = b.Uncles
	}

	return &index.FakeQueryResult[index.SideBlock]{
		NextFunction: func() (int, *index.SideBlock) {
			if len(uncles) == 0 {
				return 0, nil
			}

			if uncle := c.SideBlockByTemplateId(uncles[0].TemplateId); uncle != nil {
				uncles = uncles[1:]
				return 0, uncle
			}

			return 0, nil
		},
	}
}

// IterateWindow lock must be taken before this
func (c *channelEntry) IterateWindow(addWeightFunc index.SideBlockWindowAddWeightFunc) (bottomHeight uint64) {
	if c.ApiEndpoint == "" {
		return
	}

	var err error
	bottomHeight, err = index.BlocksInPPLNSWindow(c.Tip, c.Consensus, c.DifficultyFromHeight, c.SideBlockByTemplateId, c.SideBlockUnclesByTemplateId, addWeightFunc)

	if err != nil {
		log.Printf("error iterating window on %s", c.Name)
		return 0
	}

	return bottomHeight
}

func (c *channelEntry) SideBlockByTemplateId(id types.Hash) *index.SideBlock {
	if b, ok := c.Window[id]; ok {
		return b
	} else if b = getTypeFromAPI[index.SideBlock](c.ApiEndpoint, "/api/block_by_id/"+id.String()); b != nil {
		c.Window[b.TemplateId] = b
	}
	return nil
}

func (c *channelEntry) DifficultyFromHeight(height uint64) types.Difficulty {
	if d := getTypeFromAPI[types.Difficulty](c.ApiEndpoint, fmt.Sprintf("/api/main_difficulty_by_height/%d", height)); d != nil {
		return *d
	}
	return types.ZeroDifficulty
}

func (c *channelEntry) getPreviousWindow() {
	if c.ApiEndpoint == "" {
		return
	}
	for _, b := range getSideBlocksFromAPI(c.ApiEndpoint, fmt.Sprintf("/api/side_blocks_in_window?window=%d&noMainStatus", c.DesiredPruneDistance())) {
		c.Window[b.TemplateId] = b
		if c.Tip == nil || c.Tip.SideHeight < b.SideHeight {
			c.Tip = b
		}
	}
}

func (c *channelEntry) getConsensus() {
	if c.ApiEndpoint == "" {
		return
	}
	basePoolInfo := getPoolInfo(c.ApiEndpoint)

	consensusData, _ := json.Marshal(basePoolInfo.SideChain.Consensus)
	consensus, err := sidechain.NewConsensusFromJSON(consensusData)
	if err != nil {
		log.Panic(err)
	}
	c.Consensus = consensus
}

func (c *channelEntry) getPreviousBlocks() {
	if c.ApiEndpoint == "" {
		return
	}
	result := getSliceFromAPI[*index.FoundBlock](c.ApiEndpoint, fmt.Sprintf("/api/found_blocks?limit=%d", numberOfBlockHistoryToKeep))
	//sort from oldest to newest
	slices.SortFunc(result, func(a, b *index.FoundBlock) int {
		if a.MainBlock.Height < b.MainBlock.Height {
			return -1
		} else if a.MainBlock.Height > b.MainBlock.Height {
			return 1
		}
		return 0
	})
	c.PreviousBlocks = result
}

const readLimit = 8 * 1024 * 1024

func (c *channelEntry) openWebSocket() {
	if c.ApiEndpoint == "" {
		c.Ws.Store(nil)
		return
	}
	ctx, cancel := context.WithTimeout(context.Background(), time.Second*30)
	defer cancel()

	u, _ := url.Parse(c.ApiEndpoint)
	if u.Scheme == "https" {
		conn, _, err := websocket.Dial(ctx, fmt.Sprintf("wss://%s/api/events", u.Host), nil)
		if err != nil {
			c.Ws.Store(nil)
			return
		}
		conn.SetReadLimit(readLimit)
		c.Ws.Store(conn)
	} else {
		conn, _, err := websocket.Dial(ctx, fmt.Sprintf("ws://%s/api/events", u.Host), nil)
		if err != nil {
			c.Ws.Store(nil)
			return
		}
		conn.SetReadLimit(readLimit)
		c.Ws.Store(conn)
	}
}

func (c *channelEntry) readEvent() (*utils.JSONEvent, error) {
	if c.ApiEndpoint == "" {
		return nil, errors.New("nil endpoint")
	}

	ws := c.Ws.Load()
	if ws == nil {
		return nil, errors.New("nil websocket")
	}

	var event utils.JSONEvent
	ctx, cancel := context.WithTimeout(context.Background(), time.Minute*5)
	defer cancel()
	messageType, reader, err := ws.Reader(ctx)
	if messageType != websocket.MessageText {
		return nil, errors.New("message is not text")
	} else if err != nil {
		return nil, err
	}
	if buf, err := io.ReadAll(reader); err != nil {
		return nil, err
	} else if err = json.Unmarshal(buf, &event); err != nil {
		return nil, err
	}

	return &event, nil
}

func (c *channelEntry) pruneBlocks() {
	pruneDistance := c.DesiredPruneDistance()

	inChainFromTip := make([]types.Hash, 0, pruneDistance*2)

	for cur := c.Tip; cur != nil && (c.Tip.EffectiveHeight-cur.EffectiveHeight) <= pruneDistance; cur = c.Window[cur.ParentTemplateId] {
		inChainFromTip = append(inChainFromTip, cur.TemplateId)
		for _, u := range cur.Uncles {
			inChainFromTip = append(inChainFromTip, u.TemplateId)
		}
	}

	for k := range c.Window {
		if !slices.Contains(inChainFromTip, k) {
			delete(c.Window, k)
		}
	}
}