package placement

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

type resolveMediaInput struct {
	Permalink    string `json:"permalink"`
	StorageState string `json:"storage_state,omitempty"`
}

type resolveMediaOutput struct {
	MediaID string `json:"mediaId"`
}

// RunResolveMediaFromPermalink opens a Threads post page via Playwright and extracts numeric media id.
func RunResolveMediaFromPermalink(ctx context.Context, permalink, storageState string) (string, error) {
	permalink = strings.TrimSpace(permalink)
	if permalink == "" {
		return "", fmt.Errorf("permalink is required")
	}
	if endpoint := strings.TrimSpace(os.Getenv("HAIXUN_RESOLVE_MEDIA_URL")); endpoint != "" {
		return runHTTPResolveMedia(ctx, endpoint, permalink, storageState)
	}

	repoRoot, cliPath, err := resolveMediaCLI()
	if err != nil {
		return "", err
	}

	payload, err := json.Marshal(resolveMediaInput{
		Permalink:    permalink,
		StorageState: strings.TrimSpace(storageState),
	})
	if err != nil {
		return "", err
	}

	runCtx, cancel := context.WithTimeout(ctx, 90*time.Second)
	defer cancel()

	cmd := exec.CommandContext(runCtx, "npx", "tsx", cliPath)
	cmd.Dir = repoRoot
	cmd.Stdin = bytes.NewReader(payload)
	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		msg := strings.TrimSpace(stderr.String())
		if msg == "" {
			msg = err.Error()
		}
		return "", fmt.Errorf("permalink media resolve failed: %s", msg)
	}

	var out resolveMediaOutput
	if err := json.Unmarshal(stdout.Bytes(), &out); err != nil {
		return "", fmt.Errorf("permalink media resolve output parse failed: %w", err)
	}
	mediaID := strings.TrimSpace(out.MediaID)
	if mediaID == "" {
		return "", fmt.Errorf("permalink media resolve returned empty media id")
	}
	return mediaID, nil
}

func runHTTPResolveMedia(ctx context.Context, endpoint, permalink, storageState string) (string, error) {
	payload, err := json.Marshal(resolveMediaInput{Permalink: permalink, StorageState: strings.TrimSpace(storageState)})
	if err != nil {
		return "", err
	}
	runCtx, cancel := context.WithTimeout(ctx, 90*time.Second)
	defer cancel()
	url := strings.TrimRight(endpoint, "/") + "/resolve"
	req, err := http.NewRequestWithContext(runCtx, http.MethodPost, url, bytes.NewReader(payload))
	if err != nil {
		return "", err
	}
	req.Header.Set("Content-Type", "application/json")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", fmt.Errorf("permalink media resolve service failed: %w", err)
	}
	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)
	if res.StatusCode < 200 || res.StatusCode >= 300 {
		return "", fmt.Errorf("permalink media resolve service returned HTTP %d: %s", res.StatusCode, strings.TrimSpace(string(body)))
	}
	var out resolveMediaOutput
	if err := json.Unmarshal(body, &out); err != nil {
		return "", fmt.Errorf("permalink media resolve service output parse failed: %w", err)
	}
	mediaID := strings.TrimSpace(out.MediaID)
	if mediaID == "" {
		return "", fmt.Errorf("permalink media resolve service returned empty media id")
	}
	return mediaID, nil
}

func resolveMediaCLI() (repoRoot, cliPath string, err error) {
	if root := strings.TrimSpace(os.Getenv("HAIXUN_REPO_ROOT")); root != "" {
		cli := filepath.Join(root, "haixun-backend", "worker", "threads-resolve-media-cli.ts")
		if fileExists(cli) {
			return root, cli, nil
		}
		cli = filepath.Join(root, "worker", "threads-resolve-media-cli.ts")
		if fileExists(cli) {
			return root, cli, nil
		}
	}

	cwd, err := os.Getwd()
	if err != nil {
		return "", "", fmt.Errorf("resolve media cli: %w", err)
	}
	dir := cwd
	for i := 0; i < 6; i++ {
		cli := filepath.Join(dir, "haixun-backend", "worker", "threads-resolve-media-cli.ts")
		if fileExists(cli) {
			return dir, cli, nil
		}
		cli = filepath.Join(dir, "worker", "threads-resolve-media-cli.ts")
		if fileExists(cli) {
			return dir, cli, nil
		}
		parent := filepath.Dir(dir)
		if parent == dir {
			break
		}
		dir = parent
	}
	return "", "", fmt.Errorf("找不到 threads-resolve-media-cli.ts，請設定 HAIXUN_REPO_ROOT")
}