package envconfig

import (
	"fmt"
	"log/slog"
	"math"
	"net"
	"net/url"
	"os"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"time"
)

// Host returns the scheme and host. Host can be configured via the OLLAMA_HOST environment variable.
// Default is scheme "http" and host "127.0.0.1:11434"
func Host() *url.URL {
	defaultPort := "11434"

	s := strings.TrimSpace(Var("OLLAMA_HOST"))
	scheme, hostport, ok := strings.Cut(s, "://")
	switch {
	case !ok:
		scheme, hostport = "http", s
	case scheme == "http":
		defaultPort = "80"
	case scheme == "https":
		defaultPort = "443"
	}

	hostport, path, _ := strings.Cut(hostport, "/")
	host, port, err := net.SplitHostPort(hostport)
	if err != nil {
		host, port = "127.0.0.1", defaultPort
		if ip := net.ParseIP(strings.Trim(hostport, "[]")); ip != nil {
			host = ip.String()
		} else if hostport != "" {
			host = hostport
		}
	}

	if n, err := strconv.ParseInt(port, 10, 32); err != nil || n > 65535 || n < 0 {
		slog.Warn("invalid port, using default", "port", port, "default", defaultPort)
		port = defaultPort
	}

	return &url.URL{
		Scheme: scheme,
		Host:   net.JoinHostPort(host, port),
		Path:   path,
	}
}

// Origins returns a list of allowed origins. Origins can be configured via the OLLAMA_ORIGINS environment variable.
func Origins() (origins []string) {
	if s := Var("OLLAMA_ORIGINS"); s != "" {
		origins = strings.Split(s, ",")
	}

	for _, origin := range []string{"localhost", "127.0.0.1", "0.0.0.0"} {
		origins = append(origins,
			fmt.Sprintf("http://%s", origin),
			fmt.Sprintf("https://%s", origin),
			fmt.Sprintf("http://%s", net.JoinHostPort(origin, "*")),
			fmt.Sprintf("https://%s", net.JoinHostPort(origin, "*")),
		)
	}

	origins = append(origins,
		"app://*",
		"file://*",
		"tauri://*",
	)

	return origins
}

// Models returns the path to the models directory. Models directory can be configured via the OLLAMA_MODELS environment variable.
// Default is $HOME/.ollama/models
func Models() string {
	if s := Var("OLLAMA_MODELS"); s != "" {
		return s
	}

	home, err := os.UserHomeDir()
	if err != nil {
		panic(err)
	}

	return filepath.Join(home, ".ollama", "models")
}

// KeepAlive returns the duration that models stay loaded in memory. KeepAlive can be configured via the OLLAMA_KEEP_ALIVE environment variable.
// Negative values are treated as infinite. Zero is treated as no keep alive.
// Default is 5 minutes.
func KeepAlive() (keepAlive time.Duration) {
	keepAlive = 5 * time.Minute
	if s := Var("OLLAMA_KEEP_ALIVE"); s != "" {
		if d, err := time.ParseDuration(s); err == nil {
			keepAlive = d
		} else if n, err := strconv.ParseInt(s, 10, 64); err == nil {
			keepAlive = time.Duration(n) * time.Second
		}
	}

	if keepAlive < 0 {
		return time.Duration(math.MaxInt64)
	}

	return keepAlive
}

// LoadTimeout returns the duration for stall detection during model loads. LoadTimeout can be configured via the OLLAMA_LOAD_TIMEOUT environment variable.
// Zero or Negative values are treated as infinite.
// Default is 5 minutes.
func LoadTimeout() (loadTimeout time.Duration) {
	loadTimeout = 5 * time.Minute
	if s := Var("OLLAMA_LOAD_TIMEOUT"); s != "" {
		if d, err := time.ParseDuration(s); err == nil {
			loadTimeout = d
		} else if n, err := strconv.ParseInt(s, 10, 64); err == nil {
			loadTimeout = time.Duration(n) * time.Second
		}
	}

	if loadTimeout <= 0 {
		return time.Duration(math.MaxInt64)
	}

	return loadTimeout
}

func Bool(k string) func() bool {
	return func() bool {
		if s := Var(k); s != "" {
			b, err := strconv.ParseBool(s)
			if err != nil {
				return true
			}

			return b
		}

		return false
	}
}

var (
	// Debug enabled additional debug information.
	Debug = Bool("OLLAMA_DEBUG")
	// FlashAttention enables the experimental flash attention feature.
	FlashAttention = Bool("OLLAMA_FLASH_ATTENTION")
	// NoHistory disables readline history.
	NoHistory = Bool("OLLAMA_NOHISTORY")
	// NoPrune disables pruning of model blobs on startup.
	NoPrune = Bool("OLLAMA_NOPRUNE")
	// SchedSpread allows scheduling models across all GPUs.
	SchedSpread = Bool("OLLAMA_SCHED_SPREAD")
	// IntelGPU enables experimental Intel GPU detection.
	IntelGPU = Bool("OLLAMA_INTEL_GPU")
)

func String(s string) func() string {
	return func() string {
		return Var(s)
	}
}

var (
	LLMLibrary = String("OLLAMA_LLM_LIBRARY")
	TmpDir     = String("OLLAMA_TMPDIR")

	CudaVisibleDevices    = String("CUDA_VISIBLE_DEVICES")
	HipVisibleDevices     = String("HIP_VISIBLE_DEVICES")
	RocrVisibleDevices    = String("ROCR_VISIBLE_DEVICES")
	GpuDeviceOrdinal      = String("GPU_DEVICE_ORDINAL")
	HsaOverrideGfxVersion = String("HSA_OVERRIDE_GFX_VERSION")
)

func RunnersDir() (p string) {
	if p := Var("OLLAMA_RUNNERS_DIR"); p != "" {
		return p
	}

	if runtime.GOOS != "windows" {
		return
	}

	defer func() {
		if p == "" {
			slog.Error("unable to locate llm runner directory. Set OLLAMA_RUNNERS_DIR to the location of 'ollama/runners'")
		}
	}()

	// On Windows we do not carry the payloads inside the main executable
	exe, err := os.Executable()
	if err != nil {
		return
	}

	cwd, err := os.Getwd()
	if err != nil {
		return
	}

	var paths []string
	for _, root := range []string{filepath.Dir(exe), filepath.Join(filepath.Dir(exe), LibRelativeToExe()), cwd} {
		paths = append(paths,
			root,
			filepath.Join(root, runtime.GOOS+"-"+runtime.GOARCH),
			filepath.Join(root, "dist", runtime.GOOS+"-"+runtime.GOARCH),
		)
	}

	// Try a few variations to improve developer experience when building from source in the local tree
	for _, path := range paths {
		candidate := filepath.Join(path, "lib", "ollama", "runners")
		if _, err := os.Stat(candidate); err == nil {
			p = candidate
			break
		}
	}

	return p
}

func Uint(key string, defaultValue uint) func() uint {
	return func() uint {
		if s := Var(key); s != "" {
			if n, err := strconv.ParseUint(s, 10, 64); err != nil {
				slog.Warn("invalid environment variable, using default", "key", key, "value", s, "default", defaultValue)
			} else {
				return uint(n)
			}
		}

		return defaultValue
	}
}

var (
	// NumParallel sets the number of parallel model requests. NumParallel can be configured via the OLLAMA_NUM_PARALLEL environment variable.
	NumParallel = Uint("OLLAMA_NUM_PARALLEL", 0)
	// MaxRunners sets the maximum number of loaded models. MaxRunners can be configured via the OLLAMA_MAX_LOADED_MODELS environment variable.
	MaxRunners = Uint("OLLAMA_MAX_LOADED_MODELS", 0)
	// MaxQueue sets the maximum number of queued requests. MaxQueue can be configured via the OLLAMA_MAX_QUEUE environment variable.
	MaxQueue = Uint("OLLAMA_MAX_QUEUE", 512)
	// MaxVRAM sets a maximum VRAM override in bytes. MaxVRAM can be configured via the OLLAMA_MAX_VRAM environment variable.
	MaxVRAM = Uint("OLLAMA_MAX_VRAM", 0)
)

func Uint64(key string, defaultValue uint64) func() uint64 {
	return func() uint64 {
		if s := Var(key); s != "" {
			if n, err := strconv.ParseUint(s, 10, 64); err != nil {
				slog.Warn("invalid environment variable, using default", "key", key, "value", s, "default", defaultValue)
			} else {
				return n
			}
		}

		return defaultValue
	}
}

// Set aside VRAM per GPU
var GpuOverhead = Uint64("OLLAMA_GPU_OVERHEAD", 0)

type EnvVar struct {
	Name        string
	Value       any
	Description string
}

func AsMap() map[string]EnvVar {
	ret := map[string]EnvVar{
		"OLLAMA_DEBUG":             {"OLLAMA_DEBUG", Debug(), "Show additional debug information (e.g. OLLAMA_DEBUG=1)"},
		"OLLAMA_FLASH_ATTENTION":   {"OLLAMA_FLASH_ATTENTION", FlashAttention(), "Enabled flash attention"},
		"OLLAMA_GPU_OVERHEAD":      {"OLLAMA_GPU_OVERHEAD", GpuOverhead(), "Reserve a portion of VRAM per GPU (bytes)"},
		"OLLAMA_HOST":              {"OLLAMA_HOST", Host(), "IP Address for the ollama server (default 127.0.0.1:11434)"},
		"OLLAMA_KEEP_ALIVE":        {"OLLAMA_KEEP_ALIVE", KeepAlive(), "The duration that models stay loaded in memory (default \"5m\")"},
		"OLLAMA_LLM_LIBRARY":       {"OLLAMA_LLM_LIBRARY", LLMLibrary(), "Set LLM library to bypass autodetection"},
		"OLLAMA_LOAD_TIMEOUT":      {"OLLAMA_LOAD_TIMEOUT", LoadTimeout(), "How long to allow model loads to stall before giving up (default \"5m\")"},
		"OLLAMA_MAX_LOADED_MODELS": {"OLLAMA_MAX_LOADED_MODELS", MaxRunners(), "Maximum number of loaded models per GPU"},
		"OLLAMA_MAX_QUEUE":         {"OLLAMA_MAX_QUEUE", MaxQueue(), "Maximum number of queued requests"},
		"OLLAMA_MODELS":            {"OLLAMA_MODELS", Models(), "The path to the models directory"},
		"OLLAMA_NOHISTORY":         {"OLLAMA_NOHISTORY", NoHistory(), "Do not preserve readline history"},
		"OLLAMA_NOPRUNE":           {"OLLAMA_NOPRUNE", NoPrune(), "Do not prune model blobs on startup"},
		"OLLAMA_NUM_PARALLEL":      {"OLLAMA_NUM_PARALLEL", NumParallel(), "Maximum number of parallel requests"},
		"OLLAMA_ORIGINS":           {"OLLAMA_ORIGINS", Origins(), "A comma separated list of allowed origins"},
		"OLLAMA_RUNNERS_DIR":       {"OLLAMA_RUNNERS_DIR", RunnersDir(), "Location for runners"},
		"OLLAMA_SCHED_SPREAD":      {"OLLAMA_SCHED_SPREAD", SchedSpread(), "Always schedule model across all GPUs"},
		"OLLAMA_TMPDIR":            {"OLLAMA_TMPDIR", TmpDir(), "Location for temporary files"},
	}
	if runtime.GOOS != "darwin" {
		ret["CUDA_VISIBLE_DEVICES"] = EnvVar{"CUDA_VISIBLE_DEVICES", CudaVisibleDevices(), "Set which NVIDIA devices are visible"}
		ret["HIP_VISIBLE_DEVICES"] = EnvVar{"HIP_VISIBLE_DEVICES", HipVisibleDevices(), "Set which AMD devices are visible"}
		ret["ROCR_VISIBLE_DEVICES"] = EnvVar{"ROCR_VISIBLE_DEVICES", RocrVisibleDevices(), "Set which AMD devices are visible"}
		ret["GPU_DEVICE_ORDINAL"] = EnvVar{"GPU_DEVICE_ORDINAL", GpuDeviceOrdinal(), "Set which AMD devices are visible"}
		ret["HSA_OVERRIDE_GFX_VERSION"] = EnvVar{"HSA_OVERRIDE_GFX_VERSION", HsaOverrideGfxVersion(), "Override the gfx used for all detected AMD GPUs"}
		ret["OLLAMA_INTEL_GPU"] = EnvVar{"OLLAMA_INTEL_GPU", IntelGPU(), "Enable experimental Intel GPU detection"}
	}
	return ret
}

func Values() map[string]string {
	vals := make(map[string]string)
	for k, v := range AsMap() {
		vals[k] = fmt.Sprintf("%v", v.Value)
	}
	return vals
}

// Var returns an environment variable stripped of leading and trailing quotes or spaces
func Var(key string) string {
	return strings.Trim(strings.TrimSpace(os.Getenv(key)), "\"'")
}

// On windows, we keep the binary at the top directory, but
// other platforms use a "bin" directory, so this returns ".."
func LibRelativeToExe() string {
	if runtime.GOOS == "windows" {
		return "."
	}
	return ".."
}
