package app

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"

	"github.com/hjbdev/patterm/internal/preset"
)

const (
	defaultSummaryProvider = "codex"
	defaultCodexModel      = "gpt-5.4-mini"
	defaultOpenCodeModel   = "opencode-go/minimax-m2.7"
	defaultClaudeModel     = "claude-haiku-4-5"
)

type settings struct {
	AutoSummary autoSummarySettings `json:"auto_summary"`
}

type autoSummarySettings struct {
	Enabled         bool              `json:"enabled"`
	Provider        string            `json:"provider"`
	Models          map[string]string `json:"models"`
	Cadence         string            `json:"cadence"`
	QuietWindowMS   int               `json:"quiet_window_ms"`
	MinInputChars   int               `json:"min_input_chars"`
	MaxHistoryChars int               `json:"max_history_chars"`
}

func defaultSettings() settings {
	return settings{
		AutoSummary: autoSummarySettings{
			Enabled:         true,
			Provider:        defaultSummaryProvider,
			Models:          defaultSummaryModels(),
			Cadence:         "5m",
			QuietWindowMS:   3000,
			MinInputChars:   4,
			MaxHistoryChars: 12000,
		},
	}
}

func defaultSummaryModels() map[string]string {
	return map[string]string{
		"codex":    defaultCodexModel,
		"opencode": defaultOpenCodeModel,
		"claude":   defaultClaudeModel,
	}
}

func loadSettings() (settings, string, error) {
	base, err := preset.ConfigDir()
	if err != nil {
		return settings{}, "", err
	}
	path := filepath.Join(base, "settings.json")
	st := defaultSettings()
	b, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return st, path, nil
		}
		return st, path, fmt.Errorf("settings: read %s: %w", path, err)
	}
	if err := json.Unmarshal(b, &st); err != nil {
		return defaultSettings(), path, fmt.Errorf("settings: parse %s: %w", path, err)
	}
	st.normalize()
	return st, path, nil
}

func saveSettings(path string, st settings) error {
	if path == "" {
		return fmt.Errorf("settings: empty path")
	}
	st.normalize()
	if err := os.MkdirAll(filepath.Dir(path), 0o700); err != nil {
		return err
	}
	b, err := json.MarshalIndent(st, "", "  ")
	if err != nil {
		return err
	}
	b = append(b, '\n')
	return os.WriteFile(path, b, 0o600)
}

func (st *settings) normalize() {
	def := defaultSettings()
	if st.AutoSummary.Provider == "" {
		st.AutoSummary.Provider = def.AutoSummary.Provider
	}
	switch st.AutoSummary.Provider {
	case "codex", "opencode", "claude":
	default:
		st.AutoSummary.Provider = def.AutoSummary.Provider
	}
	if st.AutoSummary.Models == nil {
		st.AutoSummary.Models = defaultSummaryModels()
	} else {
		for k, v := range defaultSummaryModels() {
			if st.AutoSummary.Models[k] == "" {
				st.AutoSummary.Models[k] = v
			}
		}
	}
	if st.AutoSummary.Cadence == "" {
		st.AutoSummary.Cadence = def.AutoSummary.Cadence
	}
	if st.AutoSummary.QuietWindowMS <= 0 {
		st.AutoSummary.QuietWindowMS = def.AutoSummary.QuietWindowMS
	}
	if st.AutoSummary.MinInputChars <= 0 {
		st.AutoSummary.MinInputChars = def.AutoSummary.MinInputChars
	}
	if st.AutoSummary.MaxHistoryChars <= 0 {
		st.AutoSummary.MaxHistoryChars = def.AutoSummary.MaxHistoryChars
	}
}

func (st settings) clone() settings {
	st.normalize()
	if st.AutoSummary.Models != nil {
		models := make(map[string]string, len(st.AutoSummary.Models))
		for k, v := range st.AutoSummary.Models {
			models[k] = v
		}
		st.AutoSummary.Models = models
	}
	return st
}

func (a autoSummarySettings) clone() autoSummarySettings {
	st := settings{AutoSummary: a}.clone()
	return st.AutoSummary
}

func (a autoSummarySettings) modelFor(provider string) string {
	if a.Models == nil {
		return defaultSummaryModels()[provider]
	}
	if m := a.Models[provider]; m != "" {
		return m
	}
	return defaultSummaryModels()[provider]
}