package config

import (
	"fmt"
	"net"
	"time"
)

// Transformer is a function which takes configuration and applies some filter to it
type Transformer func(c *Config) error

// Profile contains the profile transformer the description of the profile
type Profile struct {
	// Description briefly describes the functionality of the profile.
	Description string

	// Transform takes ipfs configuration and applies the profile to it.
	Transform Transformer

	// InitOnly specifies that this profile can only be applied on init.
	InitOnly bool
}

// defaultServerFilters has is a list of IPv4 and IPv6 prefixes that are private, local only, or unrouteable.
// according to https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml
// and https://www.iana.org/assignments/iana-ipv6-special-registry/iana-ipv6-special-registry.xhtml
var defaultServerFilters = []string{
	"/ip4/10.0.0.0/ipcidr/8",
	"/ip4/100.64.0.0/ipcidr/10",
	"/ip4/169.254.0.0/ipcidr/16",
	"/ip4/172.16.0.0/ipcidr/12",
	"/ip4/192.0.0.0/ipcidr/24",
	"/ip4/192.0.2.0/ipcidr/24",
	"/ip4/192.168.0.0/ipcidr/16",
	"/ip4/198.18.0.0/ipcidr/15",
	"/ip4/198.51.100.0/ipcidr/24",
	"/ip4/203.0.113.0/ipcidr/24",
	"/ip4/240.0.0.0/ipcidr/4",
	"/ip6/100::/ipcidr/64",
	"/ip6/2001:2::/ipcidr/48",
	"/ip6/2001:db8::/ipcidr/32",
	"/ip6/fc00::/ipcidr/7",
	"/ip6/fe80::/ipcidr/10",
}

// Profiles is a map holding configuration transformers. Docs are in docs/config.md
var Profiles = map[string]Profile{
	"server": {
		Description: `Disables local host discovery, recommended when
running IPFS on machines with public IPv4 addresses.`,

		Transform: func(c *Config) error {
			c.Addresses.NoAnnounce = appendSingle(c.Addresses.NoAnnounce, defaultServerFilters)
			c.Swarm.AddrFilters = appendSingle(c.Swarm.AddrFilters, defaultServerFilters)
			c.Discovery.MDNS.Enabled = false
			c.Swarm.DisableNatPortMap = true
			return nil
		},
	},

	"local-discovery": {
		Description: `Sets default values to fields affected by the server
profile, enables discovery in local networks.`,

		Transform: func(c *Config) error {
			c.Addresses.NoAnnounce = deleteEntries(c.Addresses.NoAnnounce, defaultServerFilters)
			c.Swarm.AddrFilters = deleteEntries(c.Swarm.AddrFilters, defaultServerFilters)
			c.Discovery.MDNS.Enabled = true
			c.Swarm.DisableNatPortMap = false
			return nil
		},
	},
	"test": {
		Description: `Reduces external interference of IPFS daemon, this
is useful when using the daemon in test environments.`,

		Transform: func(c *Config) error {
			c.Addresses.API = Strings{"/ip4/127.0.0.1/tcp/0"}
			c.Addresses.Gateway = Strings{"/ip4/127.0.0.1/tcp/0"}
			c.Addresses.Swarm = []string{
				"/ip4/127.0.0.1/tcp/0",
			}

			c.Swarm.DisableNatPortMap = true

			c.Bootstrap = []string{}
			c.Discovery.MDNS.Enabled = false
			return nil
		},
	},
	"default-networking": {
		Description: `Restores default network settings.
Inverse profile of the test profile.`,

		Transform: func(c *Config) error {
			c.Addresses = addressesConfig()

			bootstrapPeers, err := DefaultBootstrapPeers()
			if err != nil {
				return err
			}
			c.Bootstrap = appendSingle(c.Bootstrap, BootstrapPeerStrings(bootstrapPeers))

			c.Swarm.DisableNatPortMap = false
			c.Discovery.MDNS.Enabled = true
			return nil
		},
	},
	"default-datastore": {
		Description: `Configures the node to use the default datastore (flatfs).

Read the "flatfs" profile description for more information on this datastore.

This profile may only be applied when first initializing the node.
`,

		InitOnly: true,
		Transform: func(c *Config) error {
			c.Datastore.Spec = flatfsSpec()
			return nil
		},
	},
	"flatfs": {
		Description: `Configures the node to use the flatfs datastore.

This is the most battle-tested and reliable datastore. 
You should use this datastore if:

* You need a very simple and very reliable datastore, and you trust your
  filesystem. This datastore stores each block as a separate file in the
  underlying filesystem so it's unlikely to loose data unless there's an issue
  with the underlying file system.
* You need to run garbage collection in a way that reclaims free space as soon as possible.
* You want to minimize memory usage.
* You are ok with the default speed of data import, or prefer to use --nocopy.

This profile may only be applied when first initializing the node.
`,

		InitOnly: true,
		Transform: func(c *Config) error {
			c.Datastore.Spec = flatfsSpec()
			return nil
		},
	},
	"badgerds": {
		Description: `Configures the node to use the experimental badger datastore.

Use this datastore if some aspects of performance, 
especially the speed of adding many gigabytes of files, are critical.
However, be aware that:

* This datastore will not properly reclaim space when your datastore is
  smaller than several gigabytes.  If you run IPFS with --enable-gc, you plan
  on storing very little data in your IPFS node, and disk usage is more
  critical than performance, consider using flatfs.
* This datastore uses up to several gigabytes of memory.  
* Good for medium-size datastores, but may run into performance issues
  if your dataset is bigger than a terabyte.
* The current implementation is based on old badger 1.x
  which is no longer supported by the upstream team.

This profile may only be applied when first initializing the node.`,

		InitOnly: true,
		Transform: func(c *Config) error {
			c.Datastore.Spec = badgerSpec()
			return nil
		},
	},
	"lowpower": {
		Description: `Reduces daemon overhead on the system. May affect node
functionality - performance of content discovery and data
fetching may be degraded.
`,
		Transform: func(c *Config) error {
			c.Routing.Type = NewOptionalString("dhtclient") // TODO: https://github.com/ipfs/kubo/issues/9480
			c.AutoNAT.ServiceMode = AutoNATServiceDisabled
			c.Reprovider.Interval = NewOptionalDuration(0)

			lowWater := int64(20)
			highWater := int64(40)
			gracePeriod := time.Minute
			c.Swarm.ConnMgr.Type = NewOptionalString("basic")
			c.Swarm.ConnMgr.LowWater = &OptionalInteger{value: &lowWater}
			c.Swarm.ConnMgr.HighWater = &OptionalInteger{value: &highWater}
			c.Swarm.ConnMgr.GracePeriod = &OptionalDuration{&gracePeriod}
			return nil
		},
	},
	"randomports": {
		Description: `Use a random port number for swarm.`,

		Transform: func(c *Config) error {
			port, err := getAvailablePort()
			if err != nil {
				return err
			}
			c.Addresses.Swarm = []string{
				fmt.Sprintf("/ip4/0.0.0.0/tcp/%d", port),
				fmt.Sprintf("/ip6/::/tcp/%d", port),
			}
			return nil
		},
	},
}

func getAvailablePort() (port int, err error) {
	ln, err := net.Listen("tcp", "[::]:0")
	if err != nil {
		return 0, err
	}
	defer ln.Close()
	port = ln.Addr().(*net.TCPAddr).Port
	return port, nil
}

func appendSingle(a []string, b []string) []string {
	out := make([]string, 0, len(a)+len(b))
	m := map[string]bool{}
	for _, f := range a {
		if !m[f] {
			out = append(out, f)
		}
		m[f] = true
	}
	for _, f := range b {
		if !m[f] {
			out = append(out, f)
		}
		m[f] = true
	}
	return out
}

func deleteEntries(arr []string, del []string) []string {
	m := map[string]struct{}{}
	for _, f := range arr {
		m[f] = struct{}{}
	}
	for _, f := range del {
		delete(m, f)
	}
	return mapKeys(m)
}

func mapKeys(m map[string]struct{}) []string {
	out := make([]string, 0, len(m))
	for f := range m {
		out = append(out, f)
	}
	return out
}