package config

import (
	"fmt"
	"strconv"
	"strings"
)

// sampleEntry is one line pair in the sample env file: a comment and the
// (usually commented-out) KEY=VALUE line.
type sampleEntry struct {
	name    string
	value   string
	comment string
	active  bool // rendered uncommented
}

// appVerComment documents APP_VER wherever it is rendered.
const appVerComment = `Version to run: "dev" disables updates, "stable" tracks the latest release, or pin an exact release like v0.1.7`

// sampleEntries lists every setting in sample order. logFile activates the
// LOG_FILE line (Windows install); empty keeps it commented like the rest.
// CFG_VER and APP_VER are not entries — they head the file, always active.
func sampleEntries(logFile string) []sampleEntry {
	return []sampleEntry{
		{"LISTEN_OLLAMA", ":11434", "Listen address for Ollama-compatible clients (gpu-turnstile poses as Ollama here)", false},
		{"LISTEN_COMFY", ":8188", "Listen address for ComfyUI clients (gpu-turnstile poses as ComfyUI here)", false},
		{"OLLAMA_URL", "http://127.0.0.1:11434", "Ollama upstream URL; setting it enables the Ollama consumer (default: empty = disabled)", false},
		{"COMFY_URL", "http://127.0.0.1:8188", "ComfyUI upstream URL; setting it enables the ComfyUI consumer (default: empty = disabled)", false},
		{"WARM_MODEL", "", "Optional model to reload after an image job (default: empty = none)", false},
		{"COMFY_CMD", `"C:\ComfyUI\.venv\Scripts\python.exe" ComfyUI\main.py --port 8188`, "Spawn and supervise ComfyUI on demand: the first request starts it, it stops after COMFY_IDLE_TIMEOUT to free VRAM (default: empty = unmanaged)", false},
		{"COMFY_DIR", `C:\ComfyUI`, "Working directory for COMFY_CMD (default: empty = inherit)", false},
		{"COMFY_IDLE_TIMEOUT", "5m", "Stop the managed ComfyUI after this long without requests or jobs (frees VRAM)", false},
		{"COMFY_START_TIMEOUT", "2m", "How long a request waits for the managed ComfyUI to come up", false},
		{"GAME_PROCS", "cyberpunk2077.exe,hl2.exe", "While a listed process runs, the GPU counts as held by it: requests wait, Ollama unloads, managed ComfyUI stops (default: empty = disabled)", false},
		{"GPU_FOREIGN_VRAM_MB", "1024", "Also treat the GPU as held when a process not in GPU_IGNORE_PROCS uses more VRAM than this (needs nvidia-smi; 0/empty = disabled)", false},
		{"GPU_IGNORE_PROCS", "ollama,ollama app,ollama_llama_server,python,pythonw", "Process names never counted as foreign GPU users (ComfyUI runs under python)", false},
		{"GAME_POLL_INTERVAL", "15s", "How often game/VRAM detection runs (nvidia-smi polls keep the GPU awake; don't go below ~10s)", false},
		{"UNLOAD_TIMEOUT", "60s", "How long to wait for Ollama to unload a model", false},
		{"JOB_TIMEOUT", "15m", "Maximum time to wait for a ComfyUI job", false},
		{"LLM_WAIT_TIMEOUT", "10m", "Max time an LLM request waits for the GPU before being answered 503 (wait mode)", false},
		{"LLM_BUSY_MODE", "wait", `How blocked LLM requests are handled: "wait" holds them, "reject" fails them immediately`, false},
		{"LLM_BUSY_STATUS", "503", "HTTP status for rejected LLM requests in reject mode (400-599, e.g. 429)", false},
		{"BUSY_RETRY_AFTER", "30", "Seconds sent as Retry-After on busy responses (both modes)", false},
		{"LOGLEVEL", "warn", `Log verbosity: debug, info, warn, error; "info" logs every request (LOG_LEVEL works too)`, false},
		{"LOG_FORMAT", "text", `Log format: "text" or "json"`, false},
		{"LOG_FILE", logFile, "Append logs to this file instead of stderr (a Windows service has no console)", logFile != ""},
		{"UNLOAD_POLL_INTERVAL", "500ms", "/api/ps poll interval while unloading", false},
		{"HISTORY_POLL_INTERVAL", "1s", "/history/<id> poll interval while a job runs", false},
		{"PROBE_TIMEOUT", "5s", "Probe timeout for the startup probe and the periodic health check", false},
		{"HEALTH_INTERVAL", "30s", "How often enabled upstreams are probed; status changes are logged", false},
		{"FREE_TIMEOUT", "30s", "Timeout for the POST /free call after an image job", false},
		{"WARM_TIMEOUT", "2m", "Timeout for the warm-model reload after an image job", false},
		{"SHUTDOWN_TIMEOUT", "10s", "Graceful shutdown timeout on SIGINT/SIGTERM", false},
		{"BACKOFF_INITIAL", "1s", "First retry wait when an upstream connection fails", false},
		{"BACKOFF_MAX", "60s", "Cap for the exponential retry backoff", false},
		{"PROMPT_CAPTURE_LIMIT", "65536", "Bytes of the /prompt response buffered to find prompt_id (pass-through unaffected)", false},
		{"AUTO_UPDATE", "true", "Poll the releases API for signed updates", false},
		{"UPDATE_INTERVAL", "6h", "Auto-update check interval", false},
		{"UPDATE_REPO", "https://git.rambossek.at/PUBLIC/gpu-turnstile", "Repository to check for releases", false},
		{"UPDATE_ASSET", "gpu-turnstile.exe", "Release asset to download", false},
	}
}

// SampleEnv renders a sample .env file covering every setting, each with a
// comment line. Everything is commented out — so all defaults apply —
// except the CFG_VER/APP_VER header and LOG_FILE when logFile is non-empty
// (a Windows service has no console). CFG_VER records the version that
// wrote the file so installs — and startups after an update — can upgrade
// it.
func SampleEnv(version, logFile string) string {
	// CFG_VER is always a concrete vX.Y.Z — never "dev". A dev build
	// stamps v0.0.0, which sorts older than any release, so the next
	// release install upgrades the file and stamps a proper version.
	cfgVer := version
	if cfgVer == "" || cfgVer == "dev" {
		cfgVer = "v0.0.0"
	}
	var b strings.Builder
	fmt.Fprintf(&b, "CFG_VER=%s\n", cfgVer)
	b.WriteString("# Config format reference, written by the installer — do not edit.\n")
	b.WriteString("# The installer uses it to append newly added settings on updates.\n\n")
	b.WriteString("# gpu-turnstile configuration\n")
	b.WriteString("# KEY=VALUE lines; \"#\" starts a comment. Every setting below is at its\n")
	b.WriteString("# default and commented out — remove the \"#\" to change it.\n")
	b.WriteString("# At least one of OLLAMA_URL / COMFY_URL must be set for the proxy to start.\n\n")
	writeEntry(&b, sampleEntry{"APP_VER", "stable", appVerComment, true})
	for _, e := range sampleEntries(logFile) {
		writeEntry(&b, e)
	}
	return b.String()
}

func writeEntry(b *strings.Builder, e sampleEntry) {
	fmt.Fprintf(b, "# %s\n", e.comment)
	if e.active {
		fmt.Fprintf(b, "%s=%s\n\n", e.name, e.value)
	} else {
		fmt.Fprintf(b, "#%s=%s\n\n", e.name, e.value)
	}
}

// SyncSample upgrades an installer-written env file: when its CFG_VER says
// it was written by an older gpu-turnstile, every setting the file does not
// mention — commented or not — is appended at the end, and CFG_VER is
// updated to version. Files without CFG_VER (hand-written or foreign),
// up-to-date files and "dev" builds are returned unchanged; changed reports
// whether the returned content differs.
func SyncSample(data, version, logFile string) (string, bool) {
	if version == "" || version == "dev" {
		return data, false
	}
	values, err := ParseEnvFile(strings.NewReader(data))
	if err != nil || values["CFG_VER"] == "" {
		return data, false // not installer-written; the caller decides
	}
	if compareVersions(values["CFG_VER"], version) >= 0 {
		return data, false // same or newer
	}

	present := make(map[string]bool)
	for _, line := range strings.Split(data, "\n") {
		line = strings.TrimSpace(strings.TrimPrefix(strings.TrimSpace(line), "#"))
		if name, _, ok := strings.Cut(line, "="); ok {
			present[strings.TrimSpace(name)] = true
		}
	}

	lines := strings.Split(data, "\n")
	for i, l := range lines {
		if strings.HasPrefix(strings.TrimSpace(l), "CFG_VER=") {
			lines[i] = "CFG_VER=" + version
			break
		}
	}
	out := strings.Join(lines, "\n")
	if !strings.HasSuffix(out, "\n") {
		out += "\n"
	}

	var b strings.Builder
	if !present["APP_VER"] {
		fmt.Fprintf(&b, "\n# Added by gpu-turnstile %s:\n", version)
		writeEntry(&b, sampleEntry{"APP_VER", "stable", appVerComment, true})
	}
	for _, e := range sampleEntries(logFile) {
		if !present[e.name] {
			fmt.Fprintf(&b, "\n# Added by gpu-turnstile %s:\n", version)
			writeEntry(&b, e)
		}
	}
	out += b.String()
	return out, out != data
}

// compareVersions orders two vX.Y.Z version strings. Unparseable versions
// (including "dev") sort before any release.
func compareVersions(a, b string) int {
	pa, oka := parseVersion(a)
	pb, okb := parseVersion(b)
	if oka != okb {
		if oka {
			return 1
		}
		return -1
	}
	for i := range pa {
		if pa[i] != pb[i] {
			if pa[i] > pb[i] {
				return 1
			}
			return -1
		}
	}
	return 0
}

func parseVersion(v string) ([3]int, bool) {
	var out [3]int
	v = strings.TrimPrefix(strings.TrimSpace(v), "v")
	parts := strings.Split(v, ".")
	if len(parts) != 3 {
		return out, false
	}
	for i, p := range parts {
		n, err := strconv.Atoi(p)
		if err != nil || n < 0 {
			return out, false
		}
		out[i] = n
	}
	return out, true
}