/*
   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"

	"strings"

	"github.com/spf13/cobra"
)

type Location struct {
	Start int
	End   int
}

type RawCommetBlock struct {
	LineNo int
	Lines  []string
}

type FileRawBlocks struct {
	Path   *string
	Blocks []RawCommetBlock
	lines  *[]string
}

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

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

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

func FindCommentBlocks(s *State, file *string) (*FileRawBlocks, error) {
	fullPath := path.Join(s.ProjectRoot, *file)
	readFile, err := os.Open(fullPath)

	if err != nil {
		return nil, err
	}
	defer readFile.Close()
	ext := filepath.Ext(*file)
	lang := s.GetLangForExt(ext)

	if lang == nil {
		println("[warn]: don't know about the language for extension '%s'", ext)
		return nil, nil
	}

	scanner := bufio.NewScanner(readFile)

	scanner.Split(bufio.ScanLines)

	var commentblocks []RawCommetBlock
	var line = 1
	var block RawCommetBlock
	var lines []string
	for scanner.Scan() {
		rawText := scanner.Text()
		lines = append(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() {
				commentblocks = append(commentblocks, block)
			}

			block = RawCommetBlock{}
		}
		line++
	}

	return &FileRawBlocks{
		file,
		commentblocks,
		&lines,
	}, nil
}

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

func JoinComments(state *State, commentMarker string, commentLines *[]string) *string {
	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 *FileRawBlocks) (*[]Block, error) {
	ext := filepath.Ext(*file.Path)
	lang := s.GetLangForExt(ext)

	if lang == nil {
		println("[warn]: don't know about the language for extension '%s'", ext)
		return nil, nil
	}

	// To keep track of opening and closing tags
	var stack CommentStack
	var blocks []Block

	for _, block := range file.Blocks {
		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'",
					*file.Path, block.LineNo,
				)
				return nil, e
			}

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

			continue

		}

		tags := s.getTags(*txt)

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

		stack.Push(&processedBlock)
		blocks = append(blocks, processedBlock)
	}

	return &blocks, nil
}

func ProcessFiles(state *State, files []string) error {
	for _, file := range files {
		blocks, err := FindCommentBlocks(state, &file)
		cobra.CheckErr(err)

		if blocks == nil {
			continue
		}

		processedBlocks, err := processCommentBlocks(state, blocks)

		cobra.CheckErr(err)

		for _, b := range *processedBlocks {
			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)
		}

	}
	return nil

}