// Package citadel provides an HTTP client adapter for the Citadel logging platform.
//
// This adapter communicates with a partner-hosted Citadel instance
// (e.g., citadel-staging.orchard9.ai) to manage environments and ship logs.
package citadel

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"time"

	"github.com/orchard9/rdev/internal/port"
)

// Client implements port.CitadelClient via HTTP.
type Client struct {
	baseURL    string
	apiKey     string
	httpClient *http.Client
	logger     *slog.Logger
}

// Ensure Client implements port.CitadelClient.
var _ port.CitadelClient = (*Client)(nil)

// Config holds configuration for the Citadel client.
type Config struct {
	// URL is the base URL of the Citadel instance (e.g., "https://citadel-staging.orchard9.ai").
	URL string
	// APIKey is the API key for authentication (starts with "ck_live_" or "ck_dev_").
	APIKey string
}

// NewClient creates a new Citadel HTTP client.
func NewClient(cfg Config, logger *slog.Logger) *Client {
	if logger == nil {
		logger = slog.Default()
	}
	return &Client{
		baseURL: cfg.URL,
		apiKey:  cfg.APIKey,
		httpClient: &http.Client{
			Timeout: 30 * time.Second,
		},
		logger: logger.With("component", "citadel_client"),
	}
}

// CreateEnvironment creates a new Citadel environment.
func (c *Client) CreateEnvironment(ctx context.Context, name string) (*port.CitadelEnvironment, error) {
	body := map[string]string{"name": name}
	data, err := json.Marshal(body)
	if err != nil {
		return nil, fmt.Errorf("marshal request: %w", err)
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/api/v1/environments", bytes.NewReader(data))
	if err != nil {
		return nil, fmt.Errorf("create request: %w", err)
	}
	c.setHeaders(req)

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("create environment request failed: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode == http.StatusConflict {
		// Environment already exists — fetch and return it
		c.logger.Info("citadel environment already exists, fetching", "name", name)
		return c.GetEnvironment(ctx, name)
	}

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return nil, c.readError(resp)
	}

	var result struct {
		TenantID string `json:"tenant_id"`
		Name     string `json:"name"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return nil, fmt.Errorf("decode response: %w", err)
	}

	c.logger.Info("citadel environment created", "name", name, "tenant_id", result.TenantID)

	return &port.CitadelEnvironment{
		TenantID: result.TenantID,
		Name:     result.Name,
	}, nil
}

// DeleteEnvironment removes a Citadel environment.
func (c *Client) DeleteEnvironment(ctx context.Context, tenantID string) error {
	req, err := http.NewRequestWithContext(ctx, http.MethodDelete, c.baseURL+"/api/v1/environments/"+tenantID, nil)
	if err != nil {
		return fmt.Errorf("create request: %w", err)
	}
	c.setHeaders(req)

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("delete environment request failed: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()

	// 404 is fine — environment may already be gone
	if resp.StatusCode == http.StatusNotFound {
		return nil
	}

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return c.readError(resp)
	}

	c.logger.Info("citadel environment deleted", "tenant_id", tenantID)
	return nil
}

// GetEnvironment returns an environment by name.
func (c *Client) GetEnvironment(ctx context.Context, name string) (*port.CitadelEnvironment, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.baseURL+"/api/v1/environments?name="+name, nil)
	if err != nil {
		return nil, fmt.Errorf("create request: %w", err)
	}
	c.setHeaders(req)

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("get environment request failed: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode == http.StatusNotFound {
		return nil, nil
	}

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return nil, c.readError(resp)
	}

	var result struct {
		TenantID string `json:"tenant_id"`
		Name     string `json:"name"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return nil, fmt.Errorf("decode response: %w", err)
	}

	return &port.CitadelEnvironment{
		TenantID: result.TenantID,
		Name:     result.Name,
	}, nil
}

// IngestEvent sends a single log event to Citadel.
func (c *Client) IngestEvent(ctx context.Context, tenantID string, event map[string]any) error {
	data, err := json.Marshal(event)
	if err != nil {
		return fmt.Errorf("marshal event: %w", err)
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/api/v1/ingest/event", bytes.NewReader(data))
	if err != nil {
		return fmt.Errorf("create request: %w", err)
	}
	c.setHeaders(req)
	req.Header.Set("X-Tenant-ID", tenantID)

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("ingest event request failed: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return c.readError(resp)
	}

	return nil
}

// IngestBatch sends a batch of log events to Citadel.
func (c *Client) IngestBatch(ctx context.Context, tenantID string, events []map[string]any) error {
	data, err := json.Marshal(events)
	if err != nil {
		return fmt.Errorf("marshal events: %w", err)
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/api/v1/ingest", bytes.NewReader(data))
	if err != nil {
		return fmt.Errorf("create request: %w", err)
	}
	c.setHeaders(req)
	req.Header.Set("X-Tenant-ID", tenantID)

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("ingest batch request failed: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return c.readError(resp)
	}

	return nil
}

// Healthy returns true if the Citadel instance is reachable.
func (c *Client) Healthy(ctx context.Context) bool {
	ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
	defer cancel()

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.baseURL+"/health", nil)
	if err != nil {
		return false
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return false
	}
	defer func() { _ = resp.Body.Close() }()

	return resp.StatusCode == http.StatusOK
}

func (c *Client) setHeaders(req *http.Request) {
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "Bearer "+c.apiKey)
}

func (c *Client) readError(resp *http.Response) error {
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 1024))
	return fmt.Errorf("citadel API error (HTTP %d): %s", resp.StatusCode, string(body))
}