// Package parser extracts named SQL queries from text content.
// It recognizes query blocks introduced by a line comment of the form:
//
//	-- name: <identifier>
//
// The content from that marker up to the next marker (or end of input) is
// captured as a Query. The API is intended to remain stable as the format
// evolves.
package parser

import (
	"regexp"
	"strings"
)

// Query represents a single named SQL query extracted from input.
// Name is the identifier provided after the "name:" marker,
// and SQL is the associated SQL text trimmed of surrounding whitespace.
type Query struct {
	Name string
	SQL  string
}

var (
	queryNamePattern = regexp.MustCompile(`(?m)^--\s+name:\s+(\w+)`)
)

// Parse scans content for named query markers and returns the discovered
// queries in order of appearance. The marker format is:
//
//	-- name: <identifier>
//
// SQL included in each query spans from its marker to the next marker or end of input,
// with surrounding whitespace trimmed. Currently, Parse always returns a nil error.
func Parse(content string) ([]Query, error) {
	indices := queryNamePattern.FindAllStringSubmatchIndex(content, -1)
	queries := make([]Query, 0, len(indices))

	for index, queryIndices := range indices {
		endOfQueryIndex := len(content)
		if index < len(indices)-1 {
			endOfQueryIndex = indices[index+1][0]
		}

		queryName := content[queryIndices[2]:queryIndices[3]]
		querySQL := content[queryIndices[1]:endOfQueryIndex]

		queries = append(queries, Query{
			Name: strings.TrimSpace(queryName),
			SQL:  strings.TrimSpace(querySQL),
		})
	}

	return queries, nil
}