package main

import (
	"sort"
	"strconv"
	"time"

	"sdr-visual-suite/internal/config"
	"sdr-visual-suite/internal/demod/gpudemod"
	"sdr-visual-suite/internal/dsp"
)

func mustParseDuration(raw string, fallback time.Duration) time.Duration {
	if raw == "" {
		return fallback
	}
	if d, err := time.ParseDuration(raw); err == nil {
		return d
	}
	return fallback
}

func buildDecoderMap(cfg config.Config) map[string]string {
	out := map[string]string{}
	if cfg.Decoder.FT8Cmd != "" {
		out["FT8"] = cfg.Decoder.FT8Cmd
	}
	if cfg.Decoder.WSPRCmd != "" {
		out["WSPR"] = cfg.Decoder.WSPRCmd
	}
	if cfg.Decoder.DMRCmd != "" {
		out["DMR"] = cfg.Decoder.DMRCmd
	}
	if cfg.Decoder.DStarCmd != "" {
		out["D-STAR"] = cfg.Decoder.DStarCmd
	}
	if cfg.Decoder.FSKCmd != "" {
		out["FSK"] = cfg.Decoder.FSKCmd
	}
	if cfg.Decoder.PSKCmd != "" {
		out["PSK"] = cfg.Decoder.PSKCmd
	}
	return out
}

func decoderKeys(cfg config.Config) []string {
	m := buildDecoderMap(cfg)
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	return keys
}

func extractSignalIQ(iq []complex64, sampleRate int, centerHz float64, sigHz float64, bwHz float64) []complex64 {
	if len(iq) == 0 || sampleRate <= 0 {
		return nil
	}
	offset := sigHz - centerHz
	decimTarget := 200000
	if decimTarget <= 0 {
		decimTarget = sampleRate
	}
	if gpudemod.Available() {
		if eng, err := gpudemod.New(len(iq), sampleRate); err == nil {
			defer eng.Close()
			if out, _, err := eng.ShiftFilterDecimate(iq, offset, bwHz, decimTarget); err == nil && len(out) > 0 {
				return out
			}
		}
	}
	shifted := dsp.FreqShift(iq, sampleRate, offset)
	cutoff := bwHz / 2
	if cutoff < 200 {
		cutoff = 200
	}
	if cutoff > float64(sampleRate)/2-1 {
		cutoff = float64(sampleRate)/2 - 1
	}
	taps := dsp.LowpassFIR(cutoff, sampleRate, 101)
	filtered := dsp.ApplyFIR(shifted, taps)
	decim := sampleRate / decimTarget
	if decim < 1 {
		decim = 1
	}
	return dsp.Decimate(filtered, decim)
}

func parseSince(raw string) (time.Time, error) {
	if raw == "" {
		return time.Time{}, nil
	}
	if ms, err := strconv.ParseInt(raw, 10, 64); err == nil {
		if ms > 1e12 {
			return time.UnixMilli(ms), nil
		}
		return time.Unix(ms, 0), nil
	}
	if t, err := time.Parse(time.RFC3339Nano, raw); err == nil {
		return t, nil
	}
	return time.Parse(time.RFC3339, raw)
}