package traceimpact

import (
	"regexp"
	"strings"
)

var (
	explicitKeyRe = regexp.MustCompile(`\b((?:UR|RS|REQ|TC|RF|RP|DI)-\d+)\b`)
	untypedKeyRe  = regexp.MustCompile(`\b([A-Z]{2,10}-\d+)\b`)
)

// ExtractedKey is a business key found in markdown.
type ExtractedKey struct {
	Key      string
	Kind     string
	Explicit bool
	Line     string
}

// ExtractKeys returns explicit UR/RS/REQ/TC-style keys and untyped ID mentions.
// Untyped mentions stay candidates and never become confirmed edges by themselves.
func ExtractKeys(markdown string) []ExtractedKey {
	lines := strings.Split(markdown, "\n")
	var out []ExtractedKey
	seen := map[string]bool{}
	for _, line := range lines {
		for _, m := range explicitKeyRe.FindAllStringSubmatch(line, -1) {
			key := m[1]
			if seen["e:"+key] {
				continue
			}
			seen["e:"+key] = true
			kind := KindRequirement
			if strings.HasPrefix(key, "TC-") {
				kind = KindTest
			}
			out = append(out, ExtractedKey{Key: key, Kind: kind, Explicit: true, Line: line})
		}
		for _, m := range untypedKeyRe.FindAllStringSubmatch(line, -1) {
			key := m[1]
			if explicitKeyRe.MatchString(key) || seen["u:"+key] || seen["e:"+key] {
				continue
			}
			seen["u:"+key] = true
			out = append(out, ExtractedKey{Key: key, Kind: KindRequirement, Explicit: false, Line: line})
		}
	}
	return out
}

// ExplicitPairsOnLine returns ordered pairs of explicit keys that share a line.
func ExplicitPairsOnLine(markdown string) [][2]string {
	var pairs [][2]string
	seen := map[string]bool{}
	for _, line := range strings.Split(markdown, "\n") {
		found := explicitKeyRe.FindAllStringSubmatch(line, -1)
		if len(found) < 2 {
			continue
		}
		for i := 0; i < len(found); i++ {
			for j := i + 1; j < len(found); j++ {
				a, b := found[i][1], found[j][1]
				k := a + ">" + b
				if seen[k] {
					continue
				}
				seen[k] = true
				pairs = append(pairs, [2]string{a, b})
			}
		}
	}
	return pairs
}