package docx

import (
	"regexp"
	"sort"
	"strings"
)

// StyleProfile represents the writing style characteristics of a resume.
type StyleProfile struct {
	ActionVerbs    []string // top 20 most frequent action verbs from bullet starts
	SummaryStyle   string   // first 2 sentences from any "Summary" or "Profile" section
	BulletPatterns []string // first 5 words of each bullet (up to 30 bullets)
}

// StyleExtractor analyzes parsed resume markdown text.
type StyleExtractor struct {
	markdown string
}

// NewStyleExtractor creates a new style extractor for the given markdown.
func NewStyleExtractor(markdown string) *StyleExtractor {
	return &StyleExtractor{markdown: markdown}
}

// Extract analyzes the markdown and returns a StyleProfile.
func (s *StyleExtractor) Extract() StyleProfile {
	return StyleProfile{
		ActionVerbs:    s.extractActionVerbs(),
		SummaryStyle:   s.extractSummary(),
		BulletPatterns: s.extractBulletPatterns(),
	}
}

// extractActionVerbs finds lines starting with bullet points, extracts the first word
// (action verb), deduplicates, and returns the top 20 by frequency.
func (s *StyleExtractor) extractActionVerbs() []string {
	lines := strings.Split(s.markdown, "\n")
	verbCount := make(map[string]int)

	for _, line := range lines {
		line = strings.TrimSpace(line)
		// Match lines starting with "- " or "* "
		if strings.HasPrefix(line, "- ") {
			line = strings.TrimPrefix(line, "- ")
		} else if strings.HasPrefix(line, "* ") {
			line = strings.TrimPrefix(line, "* ")
		} else {
			continue
		}

		// Extract first word
		fields := strings.Fields(line)
		if len(fields) > 0 {
			verb := strings.ToLower(fields[0])
			verbCount[verb]++
		}
	}

	// Sort by frequency (descending) and then alphabetically for stability
	type verbFreq struct {
		verb  string
		count int
	}
	var sorted []verbFreq
	for verb, count := range verbCount {
		sorted = append(sorted, verbFreq{verb, count})
	}

	sort.Slice(sorted, func(i, j int) bool {
		if sorted[i].count != sorted[j].count {
			return sorted[i].count > sorted[j].count
		}
		return sorted[i].verb < sorted[j].verb
	})

	var result []string
	for i, vf := range sorted {
		if i >= 20 {
			break
		}
		result = append(result, vf.verb)
	}
	return result
}

// extractSummary finds a heading matching Summary|Profile|About|Objective and
// returns the next 2 non-empty lines.
func (s *StyleExtractor) extractSummary() string {
	lines := strings.Split(s.markdown, "\n")
	headingRegex := regexp.MustCompile(`(?i)^\s*#+\s+(summary|profile|about|objective)\s*$`)

	for i, line := range lines {
		if headingRegex.MatchString(line) {
			// Collect next 2 non-empty lines
			var summaryLines []string
			for j := i + 1; j < len(lines) && len(summaryLines) < 2; j++ {
				trimmed := strings.TrimSpace(lines[j])
				if trimmed != "" && !strings.HasPrefix(trimmed, "#") {
					summaryLines = append(summaryLines, trimmed)
				}
			}
			if len(summaryLines) > 0 {
				return strings.Join(summaryLines, " ")
			}
		}
	}
	return ""
}

// extractBulletPatterns extracts the first 5 words of each bullet line (up to 30 bullets).
func (s *StyleExtractor) extractBulletPatterns() []string {
	lines := strings.Split(s.markdown, "\n")
	var patterns []string

	for _, line := range lines {
		if len(patterns) >= 30 {
			break
		}
		line = strings.TrimSpace(line)
		// Match lines starting with "- " or "* "
		if strings.HasPrefix(line, "- ") {
			line = strings.TrimPrefix(line, "- ")
		} else if strings.HasPrefix(line, "* ") {
			line = strings.TrimPrefix(line, "* ")
		} else {
			continue
		}

		// Extract first 5 words
		fields := strings.Fields(line)
		if len(fields) > 5 {
			fields = fields[:5]
		}
		if len(fields) > 0 {
			pattern := strings.Join(fields, " ")
			patterns = append(patterns, pattern)
		}
	}
	return patterns
}