// Command predictor-cli is a small HTTP client for stratoflights-predictor.
//
// It is intended for operations and development; production callers should
// use the REST API directly.
package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"strings"
	"time"
)

const usage = `predictor-cli — HTTP client for stratoflights-predictor

USAGE
  predictor-cli [--server URL] <command> [args...]

COMMANDS
  ready                              Check service health
  predict <KEY=VAL>...               Run a Tawhiri-compat prediction (key=value pairs)
  datasets list                      List stored dataset epochs
  datasets download [--latest|--epoch RFC3339]
                                     Trigger a dataset download
  datasets delete <epoch>            Delete a stored dataset
  jobs list                          List download jobs
  jobs get <id>                      Show one job
  jobs cancel <id>                   Cancel a running job

ENVIRONMENT
  PREDICTOR_SERVER   Default --server (overridden by the flag)
`

func main() {
	fs := flag.NewFlagSet("predictor-cli", flag.ContinueOnError)
	fs.Usage = func() { fmt.Fprint(os.Stderr, usage) }
	server := fs.String("server", envDefault("PREDICTOR_SERVER", "http://localhost:8080"), "predictor server URL")
	if err := fs.Parse(os.Args[1:]); err != nil {
		os.Exit(2)
	}
	args := fs.Args()
	if len(args) == 0 {
		fs.Usage()
		os.Exit(2)
	}

	c := &client{base: strings.TrimRight(*server, "/"), http: &http.Client{Timeout: 30 * time.Second}}
	if err := dispatch(c, args); err != nil {
		fmt.Fprintln(os.Stderr, "error:", err)
		os.Exit(1)
	}
}

func envDefault(name, fallback string) string {
	if v := os.Getenv(name); v != "" {
		return v
	}
	return fallback
}

func dispatch(c *client, args []string) error {
	switch args[0] {
	case "ready":
		return c.ready()
	case "predict":
		return c.predict(args[1:])
	case "datasets":
		if len(args) < 2 {
			return fmt.Errorf("usage: datasets {list|download|delete}")
		}
		switch args[1] {
		case "list":
			return c.datasetsList()
		case "download":
			return c.datasetsDownload(args[2:])
		case "delete":
			if len(args) < 3 {
				return fmt.Errorf("usage: datasets delete <epoch>")
			}
			return c.datasetsDelete(args[2])
		}
	case "jobs":
		if len(args) < 2 {
			return fmt.Errorf("usage: jobs {list|get|cancel}")
		}
		switch args[1] {
		case "list":
			return c.jobsList()
		case "get":
			if len(args) < 3 {
				return fmt.Errorf("usage: jobs get <id>")
			}
			return c.jobsGet(args[2])
		case "cancel":
			if len(args) < 3 {
				return fmt.Errorf("usage: jobs cancel <id>")
			}
			return c.jobsCancel(args[2])
		}
	}
	return fmt.Errorf("unknown command %q", args[0])
}

type client struct {
	base string
	http *http.Client
}

func (c *client) ready() error {
	return c.getPrint("/ready")
}

func (c *client) predict(kv []string) error {
	q := url.Values{}
	for _, p := range kv {
		idx := strings.IndexByte(p, '=')
		if idx <= 0 {
			return fmt.Errorf("expected key=value, got %q", p)
		}
		q.Set(p[:idx], p[idx+1:])
	}
	return c.getPrint("/api/v1/prediction?" + q.Encode())
}

func (c *client) datasetsList() error {
	return c.getPrint("/api/v1/admin/datasets")
}

func (c *client) datasetsDownload(args []string) error {
	fs := flag.NewFlagSet("datasets download", flag.ContinueOnError)
	latest := fs.Bool("latest", false, "download the latest available run")
	epoch := fs.String("epoch", "", "RFC3339 epoch to download")
	if err := fs.Parse(args); err != nil {
		return err
	}
	body := map[string]any{}
	if *latest {
		body["latest"] = true
	}
	if *epoch != "" {
		body["epoch"] = *epoch
	}
	return c.postPrint("/api/v1/admin/datasets", body)
}

func (c *client) datasetsDelete(epoch string) error {
	return c.deletePrint("/api/v1/admin/datasets/" + url.PathEscape(epoch))
}

func (c *client) jobsList() error { return c.getPrint("/api/v1/admin/jobs") }
func (c *client) jobsGet(id string) error {
	return c.getPrint("/api/v1/admin/jobs/" + url.PathEscape(id))
}
func (c *client) jobsCancel(id string) error {
	return c.deletePrint("/api/v1/admin/jobs/" + url.PathEscape(id))
}

func (c *client) getPrint(path string) error {
	resp, err := c.http.Get(c.base + path)
	if err != nil {
		return err
	}
	return printResp(resp)
}

func (c *client) postPrint(path string, body any) error {
	buf, err := json.Marshal(body)
	if err != nil {
		return err
	}
	resp, err := c.http.Post(c.base+path, "application/json", bytes.NewReader(buf))
	if err != nil {
		return err
	}
	return printResp(resp)
}

func (c *client) deletePrint(path string) error {
	req, err := http.NewRequest(http.MethodDelete, c.base+path, nil)
	if err != nil {
		return err
	}
	resp, err := c.http.Do(req)
	if err != nil {
		return err
	}
	return printResp(resp)
}

func printResp(resp *http.Response) error {
	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)
	if resp.StatusCode >= 400 {
		return fmt.Errorf("HTTP %d: %s", resp.StatusCode, strings.TrimSpace(string(body)))
	}
	// Pretty-print JSON when possible; raw bytes otherwise.
	if strings.Contains(resp.Header.Get("Content-Type"), "json") && len(body) > 0 {
		var any any
		if err := json.Unmarshal(body, &any); err == nil {
			pretty, _ := json.MarshalIndent(any, "", "  ")
			fmt.Println(string(pretty))
			return nil
		}
	}
	if len(body) > 0 {
		fmt.Println(strings.TrimSpace(string(body)))
	}
	return nil
}