/*
   Copyright © 2022 Sameer Rahmani <lxsameer@gnu.org>

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   of the License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

package core

import (
	"bufio"
	"fmt"

	"os"
	"path"
	"path/filepath"
	"sync"
	"time"

	"strings"
)

type Location struct {
	Start int
	End   int
}

type RawCommentBlock struct {
	LineNo int
	Lines  []string
	File   *File
}

type File struct {
	Path   string
	Blocks []RawCommentBlock
	Lines  []string
}

type Block struct {
	BlockType   string // Like TODO, NOTE, etc
	FilePath    *string
	Tags        []string
	Desc        string
	WrappedCode string
	Loc         Location
}
type FileRawBlock struct {
	Block RawCommentBlock
	Lang  *Lang
}

type CommentStack struct {
	storage []*Block
}

func (s *CommentStack) Push(block *Block) {
	s.storage = append(s.storage, block)
}

func (s *CommentStack) Pop() *Block {
	l := len(s.storage)
	if l == 0 {
		return nil
	}
	item := s.storage[l-1]
	s.storage = s.storage[:l-1]
	return item
}

func (b *RawCommentBlock) append(txt string) {
	b.Lines = append(b.Lines, txt)
}

func (b *RawCommentBlock) empty() bool {
	return len(b.Lines) == 0
}

func FindCommentBlocks(s *State, file string, output chan FileRawBlock, w *sync.WaitGroup) {
	fullPath := path.Join(s.ProjectRoot, file)
	readFile, err := os.Open(fullPath)

	if err != nil {
		s.ErrChannel <- err
		close(output)
		w.Done()

		return
	}

	ext := filepath.Ext(file)
	lang := s.GetLangForExt(ext)

	if lang == nil {
		close(output)
		w.Done()
		// log.Warnf("don't know about the language for extension '%s'", ext)
		return
	}

	scanner := bufio.NewScanner(readFile)

	scanner.Split(bufio.ScanLines)

	curFile := File{
		Path:   file,
		Blocks: []RawCommentBlock{},
		Lines:  []string{},
	}

	var line = 1
	block := RawCommentBlock{0, []string{}, &curFile}

	for scanner.Scan() {
		rawText := scanner.Text()
		curFile.Lines = append(curFile.Lines, rawText)

		txt := strings.TrimSpace(rawText)

		if strings.HasPrefix(txt, *lang.CommentBlockMarker) {
			if block.empty() {
				block.LineNo = line
			}
			block.append(txt)
		} else {
			if !block.empty() {
				curFile.Blocks = append(curFile.Blocks, block)
				output <- FileRawBlock{block, lang}
			}

			block = RawCommentBlock{0, []string{}, &curFile}
		}
		line++
	}

	if err = readFile.Close(); err != nil {

		close(output)
		w.Done()
		s.ErrChannel <- err
		return
	}

	w.Done()
	close(output)
}

func getBlockFirstLine(lang *Lang, block RawCommentBlock) *string {
	txt := strings.TrimLeft(block.Lines[0], *lang.CommentBlockMarker)
	txt = strings.TrimSpace(txt)
	return &txt
}

func JoinComments(state *State, commentMarker string, b RawCommentBlock) *string {
	commentLines := b.Lines
	firstLine := state.TrimTypeAndTags(&commentLines[0])
	result := []string{}

	if firstLine != nil {
		result = append(result, *firstLine)
	}

	if len(commentLines) > 1 {
		for _, line := range (commentLines)[1:] {
			trimmed := strings.TrimSpace(strings.TrimLeft(line, commentMarker))
			result = append(result, trimmed)

		}
	}

	txt := strings.Join(result, "\n")
	return &txt
}

func processCommentBlocks(s *State, file chan FileRawBlock, output chan Block, w *sync.WaitGroup) {
	defer close(output)
	defer w.Done()

	// To keep track of opening and closing tags
	var stack CommentStack

	for fileBlock := range file {

		block := fileBlock.Block
		lang := fileBlock.Lang

		if block.empty() {
			continue
		}

		txt := getBlockFirstLine(lang, block)
		type_ := s.getCommentType(*txt)

		if type_ == nil {
			type_, isClosing := s.detectClosingBlock(txt)
			if !isClosing {
				// A regular comment block, skipping
				continue
			}

			lastOpenBlock := stack.Pop()

			if lastOpenBlock == nil {
				// e := fmt.Errorf(
				// 	"closing comment with no Opening at '%s:%d'",
				// 	block.File.Path, block.LineNo,
				// )
				// s.ErrChannel <- e
				return
			}

			if type_ == &lastOpenBlock.BlockType {
				wrappedCode := []string{}
				for i := lastOpenBlock.Loc.End; i < block.LineNo; i++ {
					ithLine := (block.File.Lines)[i]
					wrappedCode = append(wrappedCode, ithLine)
				}
				lastOpenBlock.WrappedCode = strings.Join(wrappedCode, "\n")
			}

			continue

		}

		tags := s.getTags(*txt)

		processedBlock := Block{
			BlockType:   *type_,
			FilePath:    &block.File.Path,
			Tags:        tags,
			Desc:        *JoinComments(s, *lang.CommentBlockMarker, block),
			WrappedCode: "",
			Loc:         Location{block.LineNo, len(block.Lines) + block.LineNo},
		}

		stack.Push(&processedBlock)
		output <- processedBlock
	}
}

func PrintResult(state *State, res chan Block, w *sync.WaitGroup) {
	for b := range res {
		tags := strings.Join(b.Tags, ",")
		fmt.Printf("* %s at %s:%d | Tags: %s\n%s\n%s\n\n",
			b.BlockType, *b.FilePath, b.Loc.Start,
			tags,
			b.Desc,
			b.WrappedCode)
	}
	w.Done()
}

func ProcessFiles(state *State, files chan string) error {
	var workers sync.WaitGroup

	for file := range files {
		fileBlocks := make(chan FileRawBlock, 10)
		processed := make(chan Block, 100)

		if file == "utils/bazel/zlib.bzl" {
			println("file: ", file)
		}
		workers.Add(3)
		go FindCommentBlocks(state, file, fileBlocks, &workers)
		go processCommentBlocks(state, fileBlocks, processed, &workers)
		go PrintResult(state, processed, &workers)
	}

	controller := make(chan bool)
	go func() {
		workers.Wait()
		close(controller)
	}()

	select {
	case <-controller:
		println("Wait done")
	case <-time.After(time.Second * 20):
		println("timeout")
	}
	state.WaitGroup.Done()
	return nil

}