package knowledge

import (
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

type Skill struct {
	Name    string
	Content string
	Source  string
}

func LoadSoul(path string) (string, error) {
	b, err := os.ReadFile(path)
	if err != nil {
		return "", fmt.Errorf("read soul file failed: %w", err)
	}
	content := strings.TrimSpace(string(b))
	if content == "" {
		return "", fmt.Errorf("soul file is empty")
	}
	return content, nil
}

func LoadSkillSet(dir string) ([]Skill, error) {
	entries, err := os.ReadDir(dir)
	if err != nil {
		return nil, fmt.Errorf("read skills dir failed: %w", err)
	}

	skillDirs := make([]string, 0)
	for _, entry := range entries {
		if entry.IsDir() {
			skillDirs = append(skillDirs, entry.Name())
		}
	}
	sort.Strings(skillDirs)

	out := make([]Skill, 0, len(skillDirs))
	for _, skillDir := range skillDirs {
		file := filepath.Join(dir, skillDir, "skill.md")
		b, err := os.ReadFile(file)
		if err != nil {
			if os.IsNotExist(err) {
				continue
			}
			return nil, fmt.Errorf("read skill file failed: %w", err)
		}
		content := strings.TrimSpace(string(b))
		if content == "" {
			continue
		}

		name := extractSkillName(skillDir, content)
		out = append(out, Skill{
			Name:    name,
			Content: content,
			Source:  file,
		})
	}

	if len(out) == 0 {
		return nil, fmt.Errorf("no valid skills loaded from %s (expected: skills/<skill_name>/skill.md)", dir)
	}
	return out, nil
}

func extractSkillName(fileName, markdown string) string {
	for _, line := range strings.Split(markdown, "\n") {
		line = strings.TrimSpace(line)
		if !strings.HasPrefix(line, "#") {
			continue
		}
		title := strings.TrimSpace(strings.TrimLeft(line, "#"))
		title = strings.TrimSpace(strings.TrimPrefix(title, "Skill:"))
		title = strings.TrimSpace(strings.TrimPrefix(title, "skill:"))
		if title != "" {
			return title
		}
	}
	base := strings.TrimSuffix(fileName, filepath.Ext(fileName))
	if base == "" {
		return fileName
	}
	return base
}