package config

import (
	"bufio"
	"fmt"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"vrc_osc_go/internal/common"
)

type Config struct {
	OSC    OSCConfig
	VrcLog VrcLogConfig
	GUI    GUIConfig
}

type OSCConfig struct {
	Host string
	Port int
}

type VrcLogConfig struct {
	SelfName     string
	GuestNames   []string
	GuestFile    string
	StaffNames   []string
	MissingCount int
	LogPatterns  []string
}

type GUIConfig struct {
	TopMost               bool
	FontSize              int
	AutoUnmuteOnSelfLeave bool
	RefreshIntervalValue  int
	RefreshIntervalUnit   string
	HistoryRegex          string
	HistoryFromDate       string
	HistoryToDate         string
}

func Load(path string) (*Config, error) {
	cfg := &Config{
		OSC: OSCConfig{Host: "127.0.0.1", Port: 9001},
		GUI: GUIConfig{FontSize: 18, RefreshIntervalValue: 2, RefreshIntervalUnit: "sec"},
	}
	if path == "" {
		path = filepath.Join(common.RootDir(), "config", "config.toml")
	} else if !filepath.IsAbs(path) {
		path = filepath.Join(common.RootDir(), path)
	}
	file, err := os.Open(path)
	if err != nil {
		return cfg, nil
	}
	defer file.Close()

	var section string
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		line = strings.TrimPrefix(line, "\ufeff")
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
			section = strings.Trim(line, "[]")
			continue
		}
		parts := strings.SplitN(line, "=", 2)
		if len(parts) != 2 {
			continue
		}
		key := strings.TrimSpace(parts[0])
		val := strings.TrimSpace(parts[1])
		val = strings.Trim(val, "\"'")
		switch section {
		case "osc":
			switch key {
			case "host":
				cfg.OSC.Host = val
			case "port":
				if n, err := strconv.Atoi(val); err == nil {
					cfg.OSC.Port = n
				}
			}
		case "self":
			if key == "name" {
				cfg.VrcLog.SelfName = val
			}
		case "notice":
			if key == "missing_count" {
				if n, err := strconv.Atoi(val); err == nil {
					cfg.VrcLog.MissingCount = n
				}
			}
		case "vrc_log":
			if key == "patterns" {
				cfg.VrcLog.LogPatterns = parseList(val)
			}
		case "staff":
			if key == "names" {
				cfg.VrcLog.StaffNames = parseList(val)
			}
		case "guest":
			switch key {
			case "names":
				cfg.VrcLog.GuestNames = parseList(val)
			case "file":
				cfg.VrcLog.GuestFile = val
			}
		case "gui":
			switch key {
			case "top_most":
				cfg.GUI.TopMost = parseBool(val, cfg.GUI.TopMost)
			case "font_size":
				if n, err := strconv.Atoi(val); err == nil && n > 0 {
					cfg.GUI.FontSize = n
				}
			case "auto_unmute_on_self_leave":
				cfg.GUI.AutoUnmuteOnSelfLeave = parseBool(val, cfg.GUI.AutoUnmuteOnSelfLeave)
			case "refresh_interval_value":
				if n, err := strconv.Atoi(val); err == nil && n > 0 {
					cfg.GUI.RefreshIntervalValue = n
				}
			case "refresh_interval_unit":
				cfg.GUI.RefreshIntervalUnit = normalizeRefreshIntervalUnit(val)
			case "history_regex":
				cfg.GUI.HistoryRegex = val
			case "history_from":
				cfg.GUI.HistoryFromDate = normalizeHistoryDate(val)
			case "history_to":
				cfg.GUI.HistoryToDate = normalizeHistoryDate(val)
			}
		}
	}
	if cfg.GUI.RefreshIntervalValue <= 0 {
		cfg.GUI.RefreshIntervalValue = 2
	}
	cfg.GUI.RefreshIntervalUnit = normalizeRefreshIntervalUnit(cfg.GUI.RefreshIntervalUnit)
	cfg.GUI.HistoryFromDate = normalizeHistoryDate(cfg.GUI.HistoryFromDate)
	cfg.GUI.HistoryToDate = normalizeHistoryDate(cfg.GUI.HistoryToDate)
	if cfg.VrcLog.GuestFile != "" {
		if !filepath.IsAbs(cfg.VrcLog.GuestFile) {
			cfg.VrcLog.GuestFile = filepath.Join(common.RootDir(), cfg.VrcLog.GuestFile)
		}
		if names, err := loadLines(cfg.VrcLog.GuestFile); err == nil {
			cfg.VrcLog.GuestNames = names
		}
	}
	return cfg, scanner.Err()
}

func SaveGUI(path string, gui GUIConfig) error {
	path = resolvePath(path)
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return err
	}
	data, err := os.ReadFile(path)
	if err != nil && !os.IsNotExist(err) {
		return err
	}
	content := upsertGUISection(string(data), gui)
	return os.WriteFile(path, []byte(content), 0o644)
}

func parseList(value string) []string {
	value = strings.TrimSpace(value)
	value = strings.TrimPrefix(value, "[")
	value = strings.TrimSuffix(value, "]")
	if value == "" {
		return nil
	}
	parts := strings.Split(value, ",")
	out := make([]string, 0, len(parts))
	for _, part := range parts {
		part = strings.TrimSpace(strings.Trim(part, "\"'"))
		if part != "" {
			out = append(out, part)
		}
	}
	return out
}

func parseBool(value string, fallback bool) bool {
	switch strings.ToLower(strings.TrimSpace(value)) {
	case "true", "1", "on", "yes":
		return true
	case "false", "0", "off", "no":
		return false
	default:
		return fallback
	}
}

func resolvePath(path string) string {
	if path == "" {
		return filepath.Join(common.RootDir(), "config", "config.toml")
	}
	if !filepath.IsAbs(path) {
		return filepath.Join(common.RootDir(), path)
	}
	return path
}

func upsertGUISection(existing string, gui GUIConfig) string {
	normalized := strings.ReplaceAll(existing, "\r\n", "\n")
	lines := strings.Split(normalized, "\n")
	out := make([]string, 0, len(lines)+6)
	inGUI := false
	replaced := false
	for _, raw := range lines {
		line := raw
		trimmed := strings.TrimSpace(strings.TrimPrefix(line, "\ufeff"))
		if strings.HasPrefix(trimmed, "[") && strings.HasSuffix(trimmed, "]") {
			section := strings.Trim(trimmed, "[]")
			if section == "gui" {
				if !replaced {
					appendGUISection(&out, gui)
					replaced = true
				}
				inGUI = true
				continue
			}
			if inGUI {
				inGUI = false
			}
			out = append(out, line)
			continue
		}
		if inGUI {
			continue
		}
		out = append(out, line)
	}
	if !replaced {
		if len(out) > 0 && strings.TrimSpace(out[len(out)-1]) != "" {
			out = append(out, "")
		}
		appendGUISection(&out, gui)
	}
	content := strings.Join(out, "\n")
	content = strings.TrimRight(content, "\n")
	return content + "\n"
}

func appendGUISection(out *[]string, gui GUIConfig) {
	gui.RefreshIntervalUnit = normalizeRefreshIntervalUnit(gui.RefreshIntervalUnit)
	if gui.RefreshIntervalValue <= 0 {
		gui.RefreshIntervalValue = 2
	}
	*out = append(*out,
		"[gui]",
		fmt.Sprintf("top_most = %t", gui.TopMost),
		fmt.Sprintf("font_size = %d", gui.FontSize),
		fmt.Sprintf("auto_unmute_on_self_leave = %t", gui.AutoUnmuteOnSelfLeave),
		fmt.Sprintf("refresh_interval_value = %d", gui.RefreshIntervalValue),
		fmt.Sprintf("refresh_interval_unit = %q", gui.RefreshIntervalUnit),
		fmt.Sprintf("history_regex = %q", gui.HistoryRegex),
		fmt.Sprintf("history_from = %q", gui.HistoryFromDate),
		fmt.Sprintf("history_to = %q", gui.HistoryToDate),
	)
}

func normalizeRefreshIntervalUnit(unit string) string {
	switch strings.ToLower(strings.TrimSpace(unit)) {
	case "min", "minute", "minutes":
		return "min"
	default:
		return "sec"
	}
}

func (g GUIConfig) RefreshInterval() time.Duration {
	value := g.RefreshIntervalValue
	if value <= 0 {
		value = 2
	}
	switch normalizeRefreshIntervalUnit(g.RefreshIntervalUnit) {
	case "min":
		return time.Duration(value) * time.Minute
	default:
		return time.Duration(value) * time.Second
	}
}

func normalizeHistoryDate(value string) string {
	value = strings.TrimSpace(value)
	if value == "" {
		return ""
	}
	if _, err := time.Parse("2006-01-02", value); err != nil {
		return ""
	}
	return value
}

func loadLines(path string) ([]string, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	lines := strings.Split(string(data), "\n")
	out := make([]string, 0, len(lines))
	for _, line := range lines {
		line = strings.TrimSpace(strings.TrimPrefix(line, "\ufeff"))
		if line != "" && !strings.HasPrefix(line, "#") {
			out = append(out, line)
		}
	}
	return out, nil
}