package config

import (
	"errors"
	"fmt"
	core "git.yuntuo.hk/k2safe/orbit/model"
	"net"
	"os"
	"path/filepath"
	"strconv"
	"time"

	"git.yuntuo.hk/k2safe/orbit/internal/retention"
)

type Config struct {
	ConsoleApplicationAdmin string           // ConsoleApplicationAdmin 可跨应用管理接入的唯一控制台登录名；空时禁用。
	CredentialKeyFile       string           // CredentialKeyFile 管理员 Token 保管密钥文件路径；所有服务节点共用同一密钥环。
	ArchiveRoot             string           // ArchiveRoot 私有持久归档卷绝对路径，空表示关闭后台执行器。
	ArchiveStorageID        core.ID          // ArchiveStorageID 32位小写十六进制卷身份，各节点须挂载同一物理卷。
	ArchiveMaxBytes         int64            // ArchiveMaxBytes 全卷文件预算，默认10GiB。
	ArchiveTickInterval     time.Duration    // ArchiveTickInterval 后台扫描间隔，默认10秒。
	RetentionDefaults       retention.Policy // RetentionDefaults 未保存数据库策略时使用的部署默认值。
	HTTPAddr                string
	MySQLDSN                string
	MaxOpen                 int
	MaxIdle                 int
	MetricsAddr             string
	WorkflowTickInterval    time.Duration // WorkflowTickInterval Weave 持久化推进扫描间隔，范围100ms–1m。
	ScheduleTickInterval    time.Duration // ScheduleTickInterval 计划扫描间隔，范围100ms–1m。
	RecoveryTickInterval    time.Duration // RecoveryTickInterval 执行租约恢复扫描间隔，范围100ms–1m。
	RuntimeBatchLimit       int           // RuntimeBatchLimit 每个后台批次的候选上限，范围1–100。
	ShutdownTimeout         time.Duration // ShutdownTimeout 优雅排空和关闭窗口，范围1s–5m。
	WorkerConnectionLimit   int           // WorkerConnectionLimit 单节点 Worker WebSocket 连接上限，范围1–4096。
	EventConnectionLimit    int           // EventConnectionLimit 单节点 Event WebSocket 连接上限，范围1–4096。
	DispatchWorkers         int           // DispatchWorkers 单个 Hub 并发执行数据库领取调用的协程数，范围1–256。
	DispatchCapacity        int           // DispatchCapacity 单个 Hub 领取调用的有界内存排队槽位，范围1–65536。
}

func Load() (Config, error) { return FromEnv(os.Getenv) }
func FromEnv(get func(string) string) (Config, error) {
	c := Config{
		ConsoleApplicationAdmin: get("ORBIT_CONSOLE_APPLICATION_ADMIN"),
		CredentialKeyFile:       get("ORBIT_CREDENTIAL_KEY_FILE"),
		ArchiveRoot:             get("ORBIT_ARCHIVE_ROOT"), ArchiveStorageID: core.ID(get("ORBIT_ARCHIVE_STORAGE_ID")), ArchiveMaxBytes: 10 << 30, ArchiveTickInterval: 10 * time.Second,
		HTTPAddr:              get("ORBIT_HTTP_ADDR"),
		MySQLDSN:              get("ORBIT_MYSQL_DSN"),
		MaxOpen:               20,
		MaxIdle:               5,
		MetricsAddr:           get("ORBIT_METRICS_ADDR"),
		WorkflowTickInterval:  time.Second,
		ScheduleTickInterval:  time.Second,
		RecoveryTickInterval:  2 * time.Second,
		RuntimeBatchLimit:     100,
		ShutdownTimeout:       10 * time.Second,
		WorkerConnectionLimit: 128,
		EventConnectionLimit:  128,
		DispatchWorkers:       4,
		DispatchCapacity:      128,
	}
	if c.HTTPAddr == "" {
		c.HTTPAddr = "127.0.0.1:8080"
	}
	if _, _, err := net.SplitHostPort(c.HTTPAddr); err != nil {
		return Config{}, errors.New("invalid ORBIT_HTTP_ADDR")
	}
	if c.MySQLDSN == "" {
		return Config{}, errors.New("ORBIT_MYSQL_DSN is required")
	}
	for _, field := range []struct {
		name string
		dst  *int
	}{{"ORBIT_DB_MAX_OPEN", &c.MaxOpen}, {"ORBIT_DB_MAX_IDLE", &c.MaxIdle}} {
		if raw := get(field.name); raw != "" {
			n, err := strconv.Atoi(raw)
			if err != nil || n < 0 {
				return Config{}, fmt.Errorf("%s must be a nonnegative integer", field.name)
			}
			*field.dst = n
		}
	}
	if c.MaxOpen <= 0 || c.MaxIdle > c.MaxOpen {
		return Config{}, errors.New("database pool requires 0 <= max_idle <= max_open and max_open > 0")
	}
	for _, field := range []struct {
		name string
		dst  *time.Duration
	}{{"ORBIT_WORKFLOW_TICK_INTERVAL", &c.WorkflowTickInterval}, {"ORBIT_SCHEDULE_TICK_INTERVAL", &c.ScheduleTickInterval}, {"ORBIT_RECOVERY_TICK_INTERVAL", &c.RecoveryTickInterval}} {
		if raw := get(field.name); raw != "" {
			d, err := time.ParseDuration(raw)
			if err != nil || d < 100*time.Millisecond || d > time.Minute {
				return Config{}, fmt.Errorf("%s must be a duration from 100ms to 1m", field.name)
			}
			*field.dst = d
		}
	}
	if raw := get("ORBIT_RUNTIME_BATCH_LIMIT"); raw != "" {
		n, err := strconv.Atoi(raw)
		if err != nil || n < 1 || n > 100 {
			return Config{}, errors.New("ORBIT_RUNTIME_BATCH_LIMIT must be an integer from 1 to 100")
		}
		c.RuntimeBatchLimit = n
	}
	if raw := get("ORBIT_SHUTDOWN_TIMEOUT"); raw != "" {
		d, err := time.ParseDuration(raw)
		if err != nil || d < time.Second || d > 5*time.Minute {
			return Config{}, errors.New("ORBIT_SHUTDOWN_TIMEOUT must be a duration from 1s to 5m")
		}
		c.ShutdownTimeout = d
	}
	for _, field := range []struct {
		name string
		dst  *int
		min  int
		max  int
	}{
		{"ORBIT_WORKER_CONNECTION_LIMIT", &c.WorkerConnectionLimit, 1, 4096},
		{"ORBIT_EVENT_CONNECTION_LIMIT", &c.EventConnectionLimit, 1, 4096},
		{"ORBIT_DISPATCH_WORKERS", &c.DispatchWorkers, 1, 256},
		{"ORBIT_DISPATCH_CAPACITY", &c.DispatchCapacity, 1, 65536},
	} {
		if raw := get(field.name); raw != "" {
			n, err := strconv.Atoi(raw)
			if err != nil || n < field.min || n > field.max {
				return Config{}, fmt.Errorf("%s must be an integer from %d to %d", field.name, field.min, field.max)
			}
			*field.dst = n
		}
	}
	if c.MetricsAddr != "" {
		_, port, err := net.SplitHostPort(c.MetricsAddr)
		n, parseErr := strconv.Atoi(port)
		if err != nil || parseErr != nil || n < 0 || n > 65535 {
			return Config{}, errors.New("invalid ORBIT_METRICS_ADDR")
		}
	}

	if c.ArchiveRoot != "" || c.ArchiveStorageID != "" {
		if !filepath.IsAbs(c.ArchiveRoot) || c.ArchiveStorageID.Validate() != nil {
			return Config{}, errors.New("ORBIT_ARCHIVE_ROOT and ORBIT_ARCHIVE_STORAGE_ID must be configured together")
		}
	}
	if raw := get("ORBIT_ARCHIVE_MAX_BYTES"); raw != "" {
		n, err := strconv.ParseInt(raw, 10, 64)
		if err != nil || n < 1<<20 || n > 1<<40 {
			return Config{}, errors.New("ORBIT_ARCHIVE_MAX_BYTES must be 1MiB to 1TiB")
		}
		c.ArchiveMaxBytes = n
	}
	if raw := get("ORBIT_ARCHIVE_TICK_INTERVAL"); raw != "" {
		d, err := time.ParseDuration(raw)
		if err != nil || d < time.Second || d > time.Minute {
			return Config{}, errors.New("ORBIT_ARCHIVE_TICK_INTERVAL must be 1s to 1m")
		}
		c.ArchiveTickInterval = d
	}
	var err error
	c.RetentionDefaults, err = retention.FromEnv(get)
	if err != nil {
		return Config{}, err
	}
	return c, nil
}