/*
   Copyright 2022 Erigon contributors

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package bptree

import (
	"fmt"
	"log"
	"os"
	"os/exec"
	"strconv"
)

type Node23Graph struct {
	node *Node23
}

func NewGraph(node *Node23) *Node23Graph {
	return &Node23Graph{node}
}

func (g *Node23Graph) saveDot(filename string, debug bool) {
	palette := []string{"#FDF3D0", "#DCE8FA", "#D9E7D6", "#F1CFCD", "#F5F5F5", "#E1D5E7", "#FFE6CC", "white"}
	const unexposedIndex = 0
	const exposedIndex = 1
	const updatedIndex = 2

	f, err := os.OpenFile(filename+".dot", os.O_RDWR|os.O_CREATE, 0755)
	if err != nil {
		log.Fatal(err)
	}
	defer func() {
		if err := f.Close(); err != nil {
			log.Fatal(err)
		}
	}()
	if g.node == nil {
		if _, err := f.WriteString("strict digraph {\nnode [shape=record];}\n"); err != nil {
			log.Fatal(err)
		}
		return
	}
	if _, err := f.WriteString("strict digraph {\nnode [shape=record];\n"); err != nil {
		log.Fatal(err)
	}
	for _, n := range g.node.walkNodesPostOrder() {
		left, down, right := "", "", ""
		switch n.childrenCount() {
		case 1:
			left = "<L>L"
		case 2:
			left = "<L>L"
			right = "<R>R"
		case 3:
			left = "<L>L"
			down = "<D>D"
			right = "<R>R"
		}
		var nodeID string
		if n.isLeaf {
			var next string
			if n.keyCount() > 0 {
				if n.nextKey() == nil {
					next = "nil"
				} else {
					next = strconv.FormatUint(uint64(*n.nextKey()), 10)
				}
				if debug {
					nodeID = fmt.Sprintf("k=%v %s-%v", deref(n.keys[:len(n.keys)-1]), next, n.keys)
				} else {
					nodeID = fmt.Sprintf("k=%v %s", deref(n.keys[:len(n.keys)-1]), next)
				}
			} else {
				nodeID = "k=[]"
			}
		} else {
			if debug {
				nodeID = fmt.Sprintf("k=%v-%v", deref(n.keys), n.keys)
			} else {
				nodeID = fmt.Sprintf("k=%v", deref(n.keys))
			}
		}
		var color string
		if n.exposed {
			if n.updated {
				color = palette[updatedIndex]
			} else {
				color = palette[exposedIndex]
			}
		} else {
			ensure(!n.updated, fmt.Sprintf("saveDot: node %v is not exposed but updated", n))
			color = palette[unexposedIndex]
		}
		s := fmt.Sprintf("%d [label=\"%s|{<C>%s|%s}|%s\" style=filled fillcolor=\"%s\"];\n", n.rawPointer(), left, nodeID, down, right, color)
		if _, err := f.WriteString(s); err != nil {
			log.Fatal(err)
		}
	}
	for _, n := range g.node.walkNodesPostOrder() {
		var treeLeft, treeDown, treeRight *Node23
		switch n.childrenCount() {
		case 1:
			treeLeft = n.children[0]
		case 2:
			treeLeft = n.children[0]
			treeRight = n.children[1]
		case 3:
			treeLeft = n.children[0]
			treeDown = n.children[1]
			treeRight = n.children[2]
		}
		if treeLeft != nil {
			//if _, err := f.WriteString(fmt.Sprintln(n.rawPointer(), ":L -> ", treeLeft.rawPointer(), ":C;")); err != nil {
			if _, err := f.WriteString(fmt.Sprintf("%d:L -> %d:C;\n", n.rawPointer(), treeLeft.rawPointer())); err != nil {
				log.Fatal(err)
			}
		}
		if treeDown != nil {
			//if _, err := f.WriteString(fmt.Sprintln(n.rawPointer(), ":D -> ", treeDown.rawPointer(), ":C;")); err != nil {
			if _, err := f.WriteString(fmt.Sprintf("%d:D -> %d:C;\n", n.rawPointer(), treeDown.rawPointer())); err != nil {
				log.Fatal(err)
			}
		}
		if treeRight != nil {
			//if _, err := f.WriteString(fmt.Sprintln(n.rawPointer(), ":R -> ", treeRight.rawPointer(), ":C;")); err != nil {
			if _, err := f.WriteString(fmt.Sprintf("%d:R -> %d:C;\n", n.rawPointer(), treeRight.rawPointer())); err != nil {
				log.Fatal(err)
			}
		}
	}
	if _, err := f.WriteString("}\n"); err != nil {
		log.Fatal(err)
	}
}

func (g *Node23Graph) saveDotAndPicture(filename string, debug bool) error {
	graphDir := "testdata/graph/"
	_ = os.MkdirAll(graphDir, os.ModePerm)
	filepath := graphDir + filename
	_ = os.Remove(filepath + ".dot")
	_ = os.Remove(filepath + ".png")
	g.saveDot(filepath, debug)
	dotExecutable, _ := exec.LookPath("dot")
	cmdDot := &exec.Cmd{
		Path:   dotExecutable,
		Args:   []string{dotExecutable, "-Tpng", filepath + ".dot", "-o", filepath + ".png"},
		Stdout: os.Stdout,
		Stderr: os.Stderr,
	}
	if err := cmdDot.Run(); err != nil {
		return err
	}
	return nil
}