package api

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

// Client is the CLI's HTTP client for the daemon on 127.0.0.1; the same
// contract that server.go serves.
type Client struct {
	// BaseURL is the daemon address (http://127.0.0.1:<port>).
	BaseURL string

	// HTTP is the client in use; NewClient sets it when nil.
	HTTP *http.Client
}

// NewClient builds the client for a daemon port. The caller controls time
// budgets per call via the context (daemon detection short, /speak more
// generous); the client timeout is only the hard ceiling.
func NewClient(port int) *Client {
	return &Client{
		BaseURL: fmt.Sprintf("http://127.0.0.1:%d", port),
		HTTP:    &http.Client{Timeout: 10 * time.Second},
	}
}

// HTTPError is a daemon response with an unexpected status code (e.g. 400
// validation). Network errors (daemon dead) are regular *url.Error values
// instead; the CLI distinguishes by that: show HTTP errors, fall into
// degraded mode on network errors.
type HTTPError struct {
	Status int
	Body   string
}

func (e *HTTPError) Error() string {
	return fmt.Sprintf("HTTP %d: %s", e.Status, e.Body)
}

// Status calls GET /status (daemon detection, --wait polling).
func (c *Client) Status(ctx context.Context) (*StatusResponse, error) {
	var st StatusResponse
	if err := c.do(ctx, http.MethodGet, "/status", nil, http.StatusOK, &st); err != nil {
		return nil, err
	}
	return &st, nil
}

// Speak calls POST /speak (enqueue).
func (c *Client) Speak(ctx context.Context, req SpeakRequest) (*SpeakResponse, error) {
	var resp SpeakResponse
	if err := c.do(ctx, http.MethodPost, "/speak", req, http.StatusAccepted, &resp); err != nil {
		return nil, err
	}
	return &resp, nil
}

// Cancel calls POST /cancel; returns the number of cancelled announcements.
func (c *Client) Cancel(ctx context.Context) (int, error) {
	var resp CancelResponse
	if err := c.do(ctx, http.MethodPost, "/cancel", nil, http.StatusOK, &resp); err != nil {
		return 0, err
	}
	return resp.Cancelled, nil
}

// CancelItem calls POST /cancel-item; it reports whether the id was the
// playing announcement.
func (c *Client) CancelItem(ctx context.Context, id string) (bool, error) {
	var resp CancelItemResponse
	if err := c.do(ctx, http.MethodPost, "/cancel-item", CancelItemRequest{ID: id}, http.StatusOK, &resp); err != nil {
		return false, err
	}
	return resp.Cancelled, nil
}

// SetMute calls POST /mute (muted=true) or POST /unmute (muted=false).
func (c *Client) SetMute(ctx context.Context, muted bool) error {
	path := "/mute"
	if !muted {
		path = "/unmute"
	}
	return c.do(ctx, http.MethodPost, path, nil, http.StatusOK, nil)
}

// Shutdown calls POST /shutdown (`talk daemon stop`).
func (c *Client) Shutdown(ctx context.Context) error {
	return c.do(ctx, http.MethodPost, "/shutdown", nil, http.StatusOK, nil)
}

// do is the shared core: build the request, send it, check the status,
// decode. Network errors are returned unfiltered (the caller distinguishes
// via errors.As(&HTTPError)).
func (c *Client) do(ctx context.Context, method, path string, body any, wantStatus int, out any) error {
	var rd io.Reader
	if body != nil {
		b, err := json.Marshal(body)
		if err != nil {
			return err
		}
		rd = bytes.NewReader(b)
	}
	req, err := http.NewRequestWithContext(ctx, method, c.BaseURL+path, rd)
	if err != nil {
		return err
	}
	if body != nil {
		req.Header.Set("Content-Type", "application/json")
	}
	client := c.HTTP
	if client == nil {
		client = http.DefaultClient
	}
	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(io.LimitReader(resp.Body, maxBodyBytes))
	if err != nil {
		return err
	}
	if resp.StatusCode != wantStatus {
		return &HTTPError{Status: resp.StatusCode, Body: strings.TrimSpace(string(data))}
	}
	if out == nil {
		return nil
	}
	return json.Unmarshal(data, out)
}