package parser

import (
	"fmt"

	"git.max-richter.dev/max/marka/parser/blocks"
)

// ExtractBlocks scans once, emitting:
// - data blocks: inner content between a line that's exactly "{" and a line that's exactly "}"
// - matching blocks: gaps between data blocks (excluding the brace lines themselves)
func ExtractBlocks(template string) ([]blocks.TemplateBlock, error) {
	var out []blocks.TemplateBlock
	var curlyIndex int

	const CLOSING = '}'
	const OPENING = '{'

	var start int
	var blockType blocks.BlockType

	if len(template) > 0 && template[0] == OPENING {
		curlyIndex = 1
		blockType = blocks.DataBlock
	} else {
		blockType = blocks.MatchingBlock
	}

	for i, r := range template {

		var nextCurlyIndex = curlyIndex

		switch r {
		case OPENING:
			nextCurlyIndex++
		case CLOSING:
			nextCurlyIndex--
		}

		var nextChar rune = ' '
		if i+1 < len(template) {
			nextChar = rune(template[i+1])
		}

		if curlyIndex == 0 && nextCurlyIndex == 1 {
			block, err := blocks.ParseTemplateBlock(template[start:i], blockType)
			if err != nil {
				return nil, fmt.Errorf("Failed to parse block: %w", err)
			}
			out = append(out, block)
			start = i
			blockType = blocks.DataBlock
		} else if curlyIndex == 1 && nextCurlyIndex == 0 {

			block, err := blocks.ParseTemplateBlock(template[start:i+1], blockType)
			if err != nil {
				return nil, fmt.Errorf("Failed to parse block: %w", err)
			}
			out = append(out, block)

			if nextChar == OPENING {
				start = i + 1
				blockType = blocks.DataBlock
			} else {
				start = i + 1
				blockType = blocks.MatchingBlock
			}
		}

		curlyIndex = nextCurlyIndex
	}

	// var lastBlock = out[len(out)-1]
	// if lastBlock.End == 0 {
	// 	out = out[:len(out)-1]
	// }

	return out, nil
}