package daemon

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"time"
)

// requestError is returned by postJSON/getJSON when the server responds with an error status.
type requestError struct {
	Method     string
	Path       string
	StatusCode int
	Body       string
}

func (e *requestError) Error() string {
	return fmt.Sprintf("%s %s returned %d: %s", e.Method, e.Path, e.StatusCode, e.Body)
}

// isWorkspaceNotFoundError returns true if the error is a 404 with "workspace not found" body.
func isWorkspaceNotFoundError(err error) bool {
	var reqErr *requestError
	if !errors.As(err, &reqErr) {
		return false
	}
	if reqErr.StatusCode != http.StatusNotFound {
		return false
	}
	return strings.Contains(strings.ToLower(reqErr.Body), "workspace not found")
}

// Client handles HTTP communication with the Multica server daemon API.
type Client struct {
	baseURL string
	client  *http.Client
}

// NewClient creates a new daemon API client.
func NewClient(baseURL string) *Client {
	return &Client{
		baseURL: baseURL,
		client:  &http.Client{Timeout: 30 * time.Second},
	}
}

func (c *Client) ClaimTask(ctx context.Context, runtimeID string) (*Task, error) {
	var resp struct {
		Task *Task `json:"task"`
	}
	if err := c.postJSON(ctx, fmt.Sprintf("/api/daemon/runtimes/%s/tasks/claim", runtimeID), map[string]any{}, &resp); err != nil {
		return nil, err
	}
	return resp.Task, nil
}

func (c *Client) CreatePairingSession(ctx context.Context, req map[string]string) (PairingSession, error) {
	var resp PairingSession
	if err := c.postJSON(ctx, "/api/daemon/pairing-sessions", req, &resp); err != nil {
		return PairingSession{}, err
	}
	return resp, nil
}

func (c *Client) GetPairingSession(ctx context.Context, token string) (PairingSession, error) {
	var resp PairingSession
	if err := c.getJSON(ctx, fmt.Sprintf("/api/daemon/pairing-sessions/%s", url.PathEscape(token)), &resp); err != nil {
		return PairingSession{}, err
	}
	return resp, nil
}

func (c *Client) ClaimPairingSession(ctx context.Context, token string) (PairingSession, error) {
	var resp PairingSession
	if err := c.postJSON(ctx, fmt.Sprintf("/api/daemon/pairing-sessions/%s/claim", url.PathEscape(token)), map[string]any{}, &resp); err != nil {
		return PairingSession{}, err
	}
	return resp, nil
}

func (c *Client) StartTask(ctx context.Context, taskID string) error {
	return c.postJSON(ctx, fmt.Sprintf("/api/daemon/tasks/%s/start", taskID), map[string]any{}, nil)
}

func (c *Client) ReportProgress(ctx context.Context, taskID, summary string, step, total int) error {
	return c.postJSON(ctx, fmt.Sprintf("/api/daemon/tasks/%s/progress", taskID), map[string]any{
		"summary": summary,
		"step":    step,
		"total":   total,
	}, nil)
}

func (c *Client) CompleteTask(ctx context.Context, taskID, output, branchName string) error {
	body := map[string]any{"output": output}
	if branchName != "" {
		body["branch_name"] = branchName
	}
	return c.postJSON(ctx, fmt.Sprintf("/api/daemon/tasks/%s/complete", taskID), body, nil)
}

func (c *Client) FailTask(ctx context.Context, taskID, errMsg string) error {
	return c.postJSON(ctx, fmt.Sprintf("/api/daemon/tasks/%s/fail", taskID), map[string]any{
		"error": errMsg,
	}, nil)
}

func (c *Client) SendHeartbeat(ctx context.Context, runtimeID string) error {
	return c.postJSON(ctx, "/api/daemon/heartbeat", map[string]string{
		"runtime_id": runtimeID,
	}, nil)
}

func (c *Client) Register(ctx context.Context, req map[string]any) ([]Runtime, error) {
	var resp struct {
		Runtimes []Runtime `json:"runtimes"`
	}
	if err := c.postJSON(ctx, "/api/daemon/register", req, &resp); err != nil {
		return nil, err
	}
	return resp.Runtimes, nil
}

func (c *Client) postJSON(ctx context.Context, path string, reqBody any, respBody any) error {
	var body io.Reader
	if reqBody != nil {
		data, err := json.Marshal(reqBody)
		if err != nil {
			return err
		}
		body = bytes.NewReader(data)
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+path, body)
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")

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

	if resp.StatusCode >= 400 {
		data, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
		return &requestError{Method: http.MethodPost, Path: path, StatusCode: resp.StatusCode, Body: strings.TrimSpace(string(data))}
	}
	if respBody == nil {
		io.Copy(io.Discard, resp.Body)
		return nil
	}
	return json.NewDecoder(resp.Body).Decode(respBody)
}

func (c *Client) getJSON(ctx context.Context, path string, respBody any) error {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.baseURL+path, nil)
	if err != nil {
		return err
	}

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

	if resp.StatusCode >= 400 {
		data, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
		return &requestError{Method: http.MethodGet, Path: path, StatusCode: resp.StatusCode, Body: strings.TrimSpace(string(data))}
	}
	if respBody == nil {
		io.Copy(io.Discard, resp.Body)
		return nil
	}
	return json.NewDecoder(resp.Body).Decode(respBody)
}