// Package config loads node-agent runtime configuration from environment variables.
package config

import (
	"bufio"
	"fmt"
	"os"
	"path/filepath"
	"strconv"
	"strings"
)

// LoadEnvFile reads a simple KEY=VALUE file and sets any variables that are not
// already present in the environment. This lets the Windows service (installed
// via sc.exe, which has no per-service env support) be configured by dropping an
// `agent.env` file next to the executable — no registry edits required.
//
// Lookup order: $AGENT_ENV_FILE, then `agent.env` beside the exe, then `./agent.env`.
// Lines starting with # and blank lines are ignored. Existing env vars win, so an
// operator can still override any single value at the process level.
func LoadEnvFile() {
	candidates := []string{}
	if p := os.Getenv("AGENT_ENV_FILE"); p != "" {
		candidates = append(candidates, p)
	}
	if exe, err := os.Executable(); err == nil {
		candidates = append(candidates, filepath.Join(filepath.Dir(exe), "agent.env"))
	}
	candidates = append(candidates, "agent.env")

	for _, path := range candidates {
		f, err := os.Open(path)
		if err != nil {
			continue
		}
		scanner := bufio.NewScanner(f)
		for scanner.Scan() {
			line := strings.TrimSpace(scanner.Text())
			if line == "" || strings.HasPrefix(line, "#") {
				continue
			}
			key, val, ok := strings.Cut(line, "=")
			if !ok {
				continue
			}
			key = strings.TrimSpace(key)
			val = strings.Trim(strings.TrimSpace(val), `"'`)
			if _, exists := os.LookupEnv(key); !exists {
				_ = os.Setenv(key, val)
			}
		}
		f.Close()
		return // first file found wins
	}
}

// Config holds all runtime settings for the node agent.
type Config struct {
	// NodeID is the UUID of this render node, registered in the orchestrator.
	// Must match a row in render.render_nodes.
	NodeID string

	// OrchestratorURL is the base URL of the V2 API gateway (internal network).
	// Example: http://gateway:8080  or  http://172.30.0.5:8088
	OrchestratorURL string

	// NodeHMACSecret is the shared secret sent as X-Node-Signature header.
	// Must match NODE_HMAC_SECRET in the render-svc environment.
	NodeHMACSecret string

	// Region is the datacenter/region label for this node (e.g. "iran-tehran-1").
	// The orchestrator uses it to route region-preferred jobs to this node.
	Region string

	// AEPath is the full path to the aerender.exe binary.
	// Example: C:\Program Files\Adobe\Adobe After Effects 2024\Support Files\aerender.exe
	// Leave empty to use mock rendering (for development / testing without AE).
	AEPath string

	// AfterFxPath is the full path to afterfx.exe (the AE app, used to run the
	// template scanner script). Defaults to afterfx.exe alongside aerender.exe.
	// Leave AEPath empty too to disable scanning (dev/mock).
	AfterFxPath string

	// WorkDir is the scratch directory for render temp files and AE project copies.
	WorkDir string

	// RemotionProjectDir is the Remotion project root (package.json + src/index.ts)
	// used by the code-based render engine. Empty disables Remotion jobs on this node.
	RemotionProjectDir string

	// HeartbeatIntervalSec is how often the agent sends a heartbeat to the orchestrator.
	HeartbeatIntervalSec int

	// PollIntervalSec is how long the agent waits between job-claim attempts when idle.
	PollIntervalSec int

	// AgentVersion is the semantic version string reported to the orchestrator.
	AgentVersion string

	// AEVersion is the After Effects version string reported to the orchestrator.
	// Example: "2024"
	AEVersion string

	// ListenPort is the port for the agent's own HTTP health endpoint.
	ListenPort int
}

// Load reads configuration from environment variables, returning an error
// if any required variable is missing.
func Load() (*Config, error) {
	// Pull in agent.env (if present) before reading the environment.
	LoadEnvFile()
	c := &Config{
		NodeID:               os.Getenv("NODE_ID"),
		OrchestratorURL:      getEnv("ORCHESTRATOR_URL", "http://localhost:8088"),
		NodeHMACSecret:       getEnv("NODE_HMAC_SECRET", "node-secret-change-me"),
		Region:               getEnv("NODE_REGION", ""),
		AEPath:               getEnv("AE_PATH", ""),
		AfterFxPath:          getEnv("AFTERFX_PATH", ""),
		WorkDir:              getEnv("WORK_DIR", os.TempDir()),
		RemotionProjectDir:   getEnv("REMOTION_PROJECT_DIR", ""),
		AgentVersion:         getEnv("AGENT_VERSION", "0.1.0"),
		AEVersion:            getEnv("AE_VERSION", "2024"),
		HeartbeatIntervalSec: getInt("HEARTBEAT_INTERVAL_SEC", 5),
		PollIntervalSec:      getInt("POLL_INTERVAL_SEC", 3),
		ListenPort:           getInt("LISTEN_PORT", 7777),
	}
	if c.NodeID == "" {
		return nil, fmt.Errorf("NODE_ID environment variable is required")
	}
	// Derive afterfx.exe next to aerender.exe when not explicitly set.
	if c.AfterFxPath == "" && c.AEPath != "" {
		c.AfterFxPath = filepath.Join(filepath.Dir(c.AEPath), "afterfx.exe")
	}
	return c, nil
}

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

func getInt(key string, fallback int) int {
	if v := os.Getenv(key); v != "" {
		if n, err := strconv.Atoi(v); err == nil {
			return n
		}
	}
	return fallback
}