package session

import (
	"fmt"
	"net/http"
	"sort"
	"strings"

	"agentu/internal/agent"
	"agentu/internal/config"
	"agentu/internal/llm"
)

type Manager struct {
	cfg          *config.Config
	agent        *agent.Agent
	httpClient   *http.Client
	providerName string
	provider     config.ProviderConfig
}

func NewManager(cfg *config.Config, assistant *agent.Agent, httpClient *http.Client) (*Manager, error) {
	if httpClient == nil {
		httpClient = http.DefaultClient
	}
	providerName := cfg.DefaultProviderName()
	provider, ok := cfg.Providers[providerName]
	if !ok {
		return nil, fmt.Errorf("no provider is configured")
	}
	return &Manager{
		cfg:          cfg,
		agent:        assistant,
		httpClient:   httpClient,
		providerName: providerName,
		provider:     provider,
	}, nil
}

func (m *Manager) CurrentProvider() string {
	return m.providerName
}

func (m *Manager) CurrentModel() string {
	return m.provider.Model
}

func (m *Manager) CurrentThinking() string {
	if !m.provider.ThinkingConfigured {
		return "unset"
	}
	return m.provider.Thinking
}

func (m *Manager) Info() string {
	var b strings.Builder
	fmt.Fprintf(&b, "provider: %s\n", m.CurrentProvider())
	fmt.Fprintf(&b, "model: %s\n", m.CurrentModel())
	fmt.Fprintf(&b, "thinking: %s\n", m.CurrentThinking())
	fmt.Fprintf(&b, "providers: %s\n", strings.Join(m.providerNames(), ", "))
	if len(m.provider.Models) > 0 {
		fmt.Fprintf(&b, "models: %s\n", strings.Join(m.provider.Models, ", "))
	} else {
		b.WriteString("models: any model name is accepted for this provider\n")
	}
	fmt.Fprintf(&b, "thinking levels: %s\n", strings.Join(config.ThinkingLevels(), ", "))
	b.WriteString("usage: /model provider <name> | /model model <name> | /model thinking <level>")
	return b.String()
}

func (m *Manager) SetProvider(name string) (string, error) {
	provider, ok := m.cfg.Providers[name]
	if !ok {
		return "", fmt.Errorf("unknown provider %q; available: %s", name, strings.Join(m.providerNames(), ", "))
	}
	m.providerName = name
	m.provider = provider
	m.syncAgent(llm.NewOpenAICompatibleClient(provider.BaseURL, provider.APIKey, m.httpClient))
	return "Switched provider.\n" + m.summary(), nil
}

func (m *Manager) SetModel(model string) (string, error) {
	model = strings.TrimSpace(model)
	if model == "" {
		return "", fmt.Errorf("model is required")
	}
	if len(m.provider.Models) > 0 && !contains(m.provider.Models, model) {
		return "", fmt.Errorf("model %q is not configured for provider %q; available: %s", model, m.providerName, strings.Join(m.provider.Models, ", "))
	}
	m.provider.Model = model
	m.cfg.Providers[m.providerName] = m.provider
	m.syncAgent(nil)
	return "Switched model.\n" + m.summary(), nil
}

func (m *Manager) SetThinking(level string) (string, error) {
	level = strings.ToLower(strings.TrimSpace(level))
	if !config.IsThinkingLevel(level) {
		return "", fmt.Errorf("thinking must be one of: %s", strings.Join(config.ThinkingLevels(), ", "))
	}
	m.provider.Thinking = level
	m.provider.ThinkingConfigured = true
	if m.provider.ThinkingParam == "" {
		m.provider.ThinkingParam = "thinking"
	}
	m.cfg.Providers[m.providerName] = m.provider
	m.syncAgent(nil)
	return "Updated thinking.\n" + m.summary(), nil
}

func (m *Manager) summary() string {
	return fmt.Sprintf("provider: %s\nmodel: %s\nthinking: %s", m.CurrentProvider(), m.CurrentModel(), m.CurrentThinking())
}

func (m *Manager) syncAgent(provider llm.Provider) {
	m.agent.SetRuntime(agent.RuntimeOptions{
		Provider:        provider,
		ProviderName:    m.providerName,
		Model:           m.provider.Model,
		Thinking:        m.provider.Thinking,
		ThinkingParam:   m.provider.ThinkingParam,
		ThinkingEnabled: m.provider.ThinkingConfigured,
	})
}

func (m *Manager) providerNames() []string {
	names := make([]string, 0, len(m.cfg.Providers))
	for name := range m.cfg.Providers {
		names = append(names, name)
	}
	sort.Strings(names)
	return names
}

func contains(values []string, value string) bool {
	for _, item := range values {
		if item == value {
			return true
		}
	}
	return false
}