package main

import (
	"regexp"
	"strings"
)

var emptySection = regexp.MustCompile(`(?i)^(none|nothing|n/a|-|—)\.?$`)

// cleanReport drops everything before the first "## " heading and every section that has no
// content or only "None". It returns "" when the answer has no heading at all.
func cleanReport(answer string) string {
	var out []string
	var heading string
	var body []string
	started := false

	flush := func() {
		if heading == "" {
			return
		}
		var content []string
		for _, l := range body {
			if t := strings.TrimSpace(l); t != "" {
				content = append(content, t)
			}
		}
		if len(content) == 0 || (len(content) == 1 && emptySection.MatchString(content[0])) {
			heading, body = "", nil
			return
		}
		out = append(out, heading)
		out = append(out, body...)
		heading, body = "", nil
	}

	for _, line := range strings.Split(strings.ReplaceAll(answer, "\r\n", "\n"), "\n") {
		if strings.HasPrefix(line, "## ") {
			flush()
			started = true
			heading = line
			continue
		}
		if started {
			body = append(body, line)
		}
	}
	flush()
	return strings.TrimSpace(strings.Join(out, "\n"))
}

func hasHeading(report, prefix string) bool {
	for _, line := range strings.Split(report, "\n") {
		if strings.HasPrefix(line, prefix) {
			return true
		}
	}
	return false
}

var verdictLine = regexp.MustCompile(`(?i)^verdict:\s*(request[-_ ]changes|comment|approve)\s*$`)

// splitVerdict takes the agent's explicit verdict, its last non-empty line "Verdict: <value>",
// off the answer. The verdict is "" when the line is missing, which later reads as a plain comment.
func splitVerdict(answer string) (rest, verdict string) {
	lines := strings.Split(strings.TrimRight(strings.ReplaceAll(answer, "\r\n", "\n"), " \t\n"), "\n")
	if len(lines) == 0 {
		return answer, ""
	}
	m := verdictLine.FindStringSubmatch(strings.TrimSpace(lines[len(lines)-1]))
	if m == nil {
		return answer, ""
	}
	return strings.Join(lines[:len(lines)-1], "\n"), strings.ToLower(strings.NewReplacer("_", "-", " ", "-").Replace(m[1]))
}

// Gitea's review events. Gitea stores any other value as a pending review only its author sees.
const (
	eventApproved       = "APPROVED"
	eventRequestChanges = "REQUEST_CHANGES"
	eventComment        = "COMMENT"
)

// reviewEvent maps the agent's verdict to the Gitea review event. Changes are requested and
// comments posted as the agent said; an approval is only honoured for a non-empty change whose
// report holds no red or yellow section, and anything else is a comment.
func reviewEvent(verdict, report string, nonEmptyChange bool) string {
	switch verdict {
	case "request-changes":
		return eventRequestChanges
	case "approve":
		if nonEmptyChange && !hasHeading(report, "## 🔴") && !hasHeading(report, "## 🟡") {
			return eventApproved
		}
	}
	return eventComment
}