package main

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"inbox/internal/app/runtimecodex"
	taskexecapp "inbox/internal/app/taskexec"
	"inbox/internal/client"
	"inbox/internal/domain/workflow"
)

type config struct {
	apiURL            string
	workspaceID       string
	laneID            string
	workspaceDir      string
	runnerID          string
	pollInterval      time.Duration
	heartbeatInterval time.Duration
	healthAddr        string
	codexBin          string
}

func main() {
	cfg, err := loadConfig()
	if err != nil {
		log.Fatalf("lane-worker config error: %v", err)
	}
	if err := run(cfg); err != nil {
		log.Fatalf("lane-worker failed: %v", err)
	}
}

func loadConfig() (config, error) {
	cfg := config{
		apiURL:            strings.TrimSpace(os.Getenv("INBOX_API_URL")),
		workspaceID:       strings.TrimSpace(os.Getenv("INBOX_WORKSPACE_ID")),
		laneID:            strings.TrimSpace(os.Getenv("INBOX_LANE_ID")),
		workspaceDir:      firstNonEmpty(strings.TrimSpace(os.Getenv("INBOX_WORKSPACE")), "/workspace"),
		runnerID:          firstNonEmpty(strings.TrimSpace(os.Getenv("INBOX_RUNTIME_AGENT_ID")), strings.TrimSpace(os.Getenv("HOSTNAME")), "lane-worker"),
		pollInterval:      3 * time.Second,
		heartbeatInterval: 15 * time.Second,
		healthAddr:        ":31417",
		codexBin:          firstNonEmpty(strings.TrimSpace(os.Getenv("CODEX_BIN")), "codex"),
	}
	if cfg.apiURL == "" {
		return config{}, fmt.Errorf("INBOX_API_URL is required")
	}
	if cfg.workspaceID == "" {
		return config{}, fmt.Errorf("INBOX_WORKSPACE_ID is required")
	}
	if cfg.laneID == "" {
		return config{}, fmt.Errorf("INBOX_LANE_ID is required")
	}
	return cfg, nil
}

func run(cfg config) error {
	if err := os.MkdirAll(cfg.workspaceDir, 0755); err != nil {
		return fmt.Errorf("ensure workspace dir: %w", err)
	}
	go serveHealth(cfg.healthAddr)

	httpClient := client.New(cfg.apiURL, nil)
	for {
		assignment, found, err := claimNext(context.Background(), httpClient, cfg)
		if err != nil {
			log.Printf("claim next task: %v", err)
			time.Sleep(cfg.pollInterval)
			continue
		}
		if !found {
			time.Sleep(cfg.pollInterval)
			continue
		}
		if err := executeAssignment(context.Background(), httpClient, cfg, assignment); err != nil {
			log.Printf("execute task %s: %v", assignment.Run.ID, err)
		}
	}
}

func serveHealth(addr string) {
	mux := http.NewServeMux()
	mux.HandleFunc("/healthz", func(w http.ResponseWriter, _ *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write([]byte(`{"ok":true,"service":"lane-worker"}`))
	})
	if err := http.ListenAndServe(addr, mux); err != nil {
		log.Fatalf("lane-worker health server failed: %v", err)
	}
}

func claimNext(ctx context.Context, httpClient *client.Client, cfg config) (taskexecapp.Assignment, bool, error) {
	body, err := json.Marshal(map[string]any{"runner_id": cfg.runnerID})
	if err != nil {
		return taskexecapp.Assignment{}, false, err
	}
	resp, err := httpClient.Do(ctx, http.MethodPost, "/api/v2/runtime/lanes/"+cfg.laneID+"/tasks/next", http.Header{
		"Content-Type": []string{"application/json"},
	}, body)
	if err != nil {
		return taskexecapp.Assignment{}, false, err
	}
	if resp.StatusCode == http.StatusNoContent {
		return taskexecapp.Assignment{}, false, nil
	}
	if resp.StatusCode != http.StatusOK {
		return taskexecapp.Assignment{}, false, fmt.Errorf("claim task status %d: %s", resp.StatusCode, strings.TrimSpace(string(resp.Body)))
	}
	var payload struct {
		Assignment taskexecapp.Assignment `json:"assignment"`
	}
	if err := json.Unmarshal(resp.Body, &payload); err != nil {
		return taskexecapp.Assignment{}, false, fmt.Errorf("decode assignment: %w", err)
	}
	return payload.Assignment, true, nil
}

func executeAssignment(ctx context.Context, httpClient *client.Client, cfg config, assignment taskexecapp.Assignment) error {
	log.Printf("starting task run=%s lane=%s task=%s", assignment.Run.ID, assignment.Lane.ID, assignment.Task.ID)
	tempDir, err := os.MkdirTemp("", "lane-worker-*")
	if err != nil {
		return err
	}
	defer os.RemoveAll(tempDir)

	resultFile := filepath.Join(tempDir, "result.txt")
	args := []string{
		"exec",
		"--skip-git-repo-check",
		"-C", cfg.workspaceDir,
		"--dangerously-bypass-approvals-and-sandbox",
		"-o", resultFile,
	}
	if strings.TrimSpace(assignment.Model) != "" {
		args = append(args, "-m", assignment.Model)
	}
	args = append(args, "-")

	cmd := exec.CommandContext(ctx, cfg.codexBin, args...)
	cmd.Dir = cfg.workspaceDir
	cmd.Stdin = strings.NewReader(assignment.Prompt)
	cmd.Env = roleCommandEnv(assignment)

	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return fmt.Errorf("stdout pipe: %w", err)
	}
	stderr, err := cmd.StderrPipe()
	if err != nil {
		return fmt.Errorf("stderr pipe: %w", err)
	}
	if err := cmd.Start(); err != nil {
		return fmt.Errorf("start codex exec: %w", err)
	}

	var streamWG sync.WaitGroup
	streamWG.Add(2)
	go streamLogs(&streamWG, stdout, workflow.LogStreamStdout, httpClient, assignment.Run.ID)
	go streamLogs(&streamWG, stderr, workflow.LogStreamStderr, httpClient, assignment.Run.ID)

	waitErr := cmd.Wait()
	streamWG.Wait()

	resultBytes, _ := os.ReadFile(resultFile)
	resultText := strings.TrimSpace(string(resultBytes))
	completion := taskexecapp.Completion{
		RunID:          assignment.Run.ID,
		ExitCode:       0,
		ResultMarkdown: resultText,
		Status:         workflow.RunStatusSucceeded,
	}
	if waitErr != nil {
		completion.Status = workflow.RunStatusFailed
		completion.ErrorMessage = waitErr.Error()
		if exitErr, ok := waitErr.(*exec.ExitError); ok {
			completion.ExitCode = exitErr.ExitCode()
		}
	}
	if _, err := completeRun(ctx, httpClient, completion); err != nil {
		return err
	}
	log.Printf("completed task run=%s status=%s", assignment.Run.ID, completion.Status)
	return nil
}

func streamLogs(wg *sync.WaitGroup, pipeReader io.Reader, stream workflow.LogStream, httpClient *client.Client, runID string) {
	defer wg.Done()
	scanner := bufio.NewScanner(pipeReader)
	scanner.Buffer(make([]byte, 0, 64*1024), 1024*1024)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" {
			continue
		}
		if err := appendLog(context.Background(), httpClient, runID, stream, line); err != nil {
			log.Printf("append log run=%s stream=%s: %v", runID, stream, err)
		}
	}
	if err := scanner.Err(); err != nil {
		log.Printf("log scan run=%s stream=%s: %v", runID, stream, err)
	}
}

func appendLog(ctx context.Context, httpClient *client.Client, runID string, stream workflow.LogStream, content string) error {
	body, err := json.Marshal(map[string]any{
		"stream":  stream,
		"content": content,
	})
	if err != nil {
		return err
	}
	resp, err := httpClient.Do(ctx, http.MethodPost, "/api/v2/workflow-runs/"+runID+"/logs", http.Header{
		"Content-Type": []string{"application/json"},
	}, body)
	if err != nil {
		return err
	}
	if resp.StatusCode != http.StatusCreated {
		return fmt.Errorf("append log status %d: %s", resp.StatusCode, strings.TrimSpace(string(resp.Body)))
	}
	return nil
}

func completeRun(ctx context.Context, httpClient *client.Client, completion taskexecapp.Completion) (workflow.Run, error) {
	body, err := json.Marshal(map[string]any{
		"status":          completion.Status,
		"exit_code":       completion.ExitCode,
		"result_markdown": completion.ResultMarkdown,
		"error_message":   completion.ErrorMessage,
	})
	if err != nil {
		return workflow.Run{}, err
	}
	resp, err := httpClient.Do(ctx, http.MethodPost, "/api/v2/runtime/task-executions/"+completion.RunID+"/complete", http.Header{
		"Content-Type": []string{"application/json"},
	}, body)
	if err != nil {
		return workflow.Run{}, err
	}
	if resp.StatusCode != http.StatusOK {
		return workflow.Run{}, fmt.Errorf("complete run status %d: %s", resp.StatusCode, strings.TrimSpace(string(resp.Body)))
	}
	var run workflow.Run
	if err := json.Unmarshal(resp.Body, &run); err != nil {
		return workflow.Run{}, fmt.Errorf("decode completed run: %w", err)
	}
	return run, nil
}

func roleCommandEnv(assignment taskexecapp.Assignment) []string {
	roleHome := runtimecodex.ContainerUserHomeDir()
	codexDir := runtimecodex.ContainerCodexDir()
	_ = os.MkdirAll(codexDir, 0755)

	env := append([]string{}, os.Environ()...)
	env = append(env, "HOME="+roleHome)
	env = append(env, "CODEX_HOME="+codexDir)
	return env
}

func firstNonEmpty(values ...string) string {
	for _, value := range values {
		if strings.TrimSpace(value) != "" {
			return value
		}
	}
	return ""
}