package ingest

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"
)

const obsidianConfigPath = ".config/obsidian/obsidian.json"

type ObsidianIngester struct {
	Version string
	Vault   string // optional override; empty = auto-detect
}

func NewObsidianIngester(vault string) *ObsidianIngester {
	return &ObsidianIngester{Version: "obsidian-note/v1", Vault: vault}
}

func (o *ObsidianIngester) SourceID() string { return "obsidian" }

func (o *ObsidianIngester) IngestAll() ([]*IngestResult, error) {
	vault := o.Vault
	if vault == "" {
		var err error
		vault, err = detectObsidianVault()
		if err != nil {
			return nil, fmt.Errorf("no vault path and auto-detect failed: %w", err)
		}
	}

	if !fileExists(vault) {
		return nil, fmt.Errorf("vault path %s does not exist", vault)
	}

	var results []*IngestResult
	err := filepath.Walk(vault, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil // skip errors per-file
		}
		if info.IsDir() {
			dir := filepath.Base(path)
			if strings.HasPrefix(dir, ".") || dir == "node_modules" {
				return filepath.SkipDir
			}
			return nil
		}
		if !strings.HasSuffix(path, ".md") {
			return nil
		}

		result, err := o.ingestNote(path, vault)
		if err != nil {
			return nil
		}
		if result != nil {
			results = append(results, result)
		}
		return nil
	})

	return results, err
}

func (o *ObsidianIngester) ingestNote(path, vault string) (*IngestResult, error) {
	data, err := os.ReadFile(path)
	if err != nil || len(data) < 10 {
		return nil, nil
	}

	content := string(data)
	title := extractObsidianTitle(content, path, vault)
	tags := extractObsidianTags(content)
	created, modified := extractObsidianTimestamps(content, path)
	if created == "" {
		if fi, err := os.Stat(path); err == nil {
			created = fi.ModTime().UTC().Format(time.RFC3339)
		}
	}
	if modified == "" && created != "" {
		modified = created
	}

	// Fingerprint by content (so edits create updates)
	fp := FingerprintWithMeta(data, map[string]string{
		"source": "obsidian",
		"path":   path,
	})

	relPath, _ := filepath.Rel(vault, path)
	summary := extractBodyPreview(content, 200)

	return &IngestResult{
		Fingerprint:     fp,
		SourceID:        o.SourceID(),
		SourcePath:      relPath,
		Project:         filepath.Base(vault),
		ContentType:     ".md",
		Title:           title,
		Summary:         summary,
		CreatedAt:       created,
		LineStart:       0,
		LineEnd:         len(strings.Split(content, "\n")),
		Confidence:      0.85,
		IngesterVersion: o.Version,
		Provenance: map[string]any{
			"path":        relPath,
			"tags":        tags,
			"modified_at": modified,
			"note_title":  title,
		},
	}, nil
}

func DetectObsidianVault() (string, error) { return detectObsidianVault() }
func detectObsidianVault() (string, error) {
	home, _ := os.UserHomeDir()
	cfgPath := filepath.Join(home, obsidianConfigPath)
	if !fileExists(cfgPath) {
		// Fallback: check common vault locations
		common := []string{
			filepath.Join(home, "notes"),
			filepath.Join(home, "Documents", "notes"),
			filepath.Join(home, "Obsidian"),
			filepath.Join(home, "vault"),
		}
		for _, p := range common {
			if fileExists(filepath.Join(p, ".obsidian")) {
				return p, nil
			}
		}
		return "", fmt.Errorf("no obsidian config found at %s and no common vault detected", cfgPath)
	}

	data, err := os.ReadFile(cfgPath)
	if err != nil {
		return "", err
	}

	var cfg struct {
		Vaults map[string]struct {
			Path string `json:"path"`
		} `json:"vaults"`
	}
	if err := json.Unmarshal(data, &cfg); err != nil {
		return "", fmt.Errorf("parse obsidian config: %w", err)
	}

	for _, v := range cfg.Vaults {
		if v.Path != "" {
			return v.Path, nil
		}
	}
	return "", fmt.Errorf("no vault path in obsidian config")
}

func extractObsidianTitle(content, path, vault string) string {
	// Try frontmatter title first
	for _, line := range strings.Split(content, "\n") {
		trimmed := strings.TrimSpace(line)
		if strings.HasPrefix(trimmed, "title:") {
			t := strings.TrimSpace(trimmed[6:])
			t = strings.Trim(t, "\"'")
			if t != "" {
				return t
			}
		}
		if strings.HasPrefix(trimmed, "aliases:") {
			break
		}
		if trimmed == "---" && strings.Count(content[:len(content)/2], "---") >= 2 {
			break
		}
	}

	// Fallback: first H1
	for _, line := range strings.Split(content, "\n") {
		trimmed := strings.TrimSpace(line)
		if strings.HasPrefix(trimmed, "# ") {
			return strings.TrimSpace(trimmed[2:])
		}
	}

	// Fallback: filename
	rel, _ := filepath.Rel(vault, path)
	return strings.TrimSuffix(rel, ".md")
}

func extractObsidianTags(content string) []string {
	for _, line := range strings.Split(content, "\n") {
		trimmed := strings.TrimSpace(line)
		if strings.HasPrefix(trimmed, "tags:") {
			raw := strings.TrimSpace(trimmed[5:])
			raw = strings.Trim(raw, "\"[] ")
			var tags []string
			for _, t := range strings.Split(raw, ",") {
				t = strings.TrimSpace(t)
				t = strings.Trim(t, "\" ")
				if t != "" {
					tags = append(tags, t)
				}
			}
			return tags
		}
		if trimmed == "---" && strings.Count(content[:len(content)/2], "---") >= 2 {
			break
		}
	}
	return nil
}

func extractObsidianTimestamps(content, path string) (created, modified string) {
	// Try frontmatter dates
	inFrontmatter := false
	for _, line := range strings.Split(content, "\n") {
		trimmed := strings.TrimSpace(line)
		if trimmed == "---" {
			inFrontmatter = !inFrontmatter
			continue
		}
		if !inFrontmatter {
			break
		}
		if strings.HasPrefix(trimmed, "created:") || strings.HasPrefix(trimmed, "date:") {
			created = strings.TrimSpace(trimmed[strings.Index(trimmed, ":")+1:])
			created = strings.Trim(created, "\"' ")
		}
		if strings.HasPrefix(trimmed, "modified:") || strings.HasPrefix(trimmed, "updated:") {
			modified = strings.TrimSpace(trimmed[strings.Index(trimmed, ":")+1:])
			modified = strings.Trim(modified, "\"' ")
		}
	}
	return created, modified
}

func extractBodyPreview(content string, maxLen int) string {
	inFrontmatter := false
	var body strings.Builder
	for _, line := range strings.Split(content, "\n") {
		trimmed := strings.TrimSpace(line)
		if trimmed == "---" {
			if inFrontmatter {
				inFrontmatter = false
				continue
			}
			inFrontmatter = true
			continue
		}
		if inFrontmatter {
			continue
		}
		if trimmed != "" && body.Len() < maxLen {
			if body.Len() > 0 {
				body.WriteString(" ")
			}
			body.WriteString(truncate(trimmed, maxLen-body.Len()))
		}
	}
	result := body.String()
	if len(result) > maxLen {
		return result[:maxLen] + "..."
	}
	return result
}