package control

import (
    "encoding/json"
    "net/http"
    "sync"

    "github.com/jan/fm-rds-tx/internal/config"
    drypkg "github.com/jan/fm-rds-tx/internal/dryrun"
)

type Server struct {
    mu  sync.RWMutex
    cfg config.Config
}

type ConfigPatch struct {
    FrequencyMHz *float64 `json:"frequencyMHz,omitempty"`
    OutputDrive  *float64 `json:"outputDrive,omitempty"`
    ToneLeftHz   *float64 `json:"toneLeftHz,omitempty"`
    ToneRightHz  *float64 `json:"toneRightHz,omitempty"`
    ToneAmplitude *float64 `json:"toneAmplitude,omitempty"`
    PS           *string  `json:"ps,omitempty"`
    RadioText    *string  `json:"radioText,omitempty"`
}

func NewServer(cfg config.Config) *Server { return &Server{cfg: cfg} }

func (s *Server) Handler() http.Handler {
    mux := http.NewServeMux()
    mux.HandleFunc("/healthz", s.handleHealth)
    mux.HandleFunc("/status", s.handleStatus)
    mux.HandleFunc("/dry-run", s.handleDryRun)
    mux.HandleFunc("/config", s.handleConfig)
    return mux
}

func (s *Server) handleHealth(w http.ResponseWriter, _ *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    _ = json.NewEncoder(w).Encode(map[string]any{"ok": true})
}

func (s *Server) handleStatus(w http.ResponseWriter, _ *http.Request) {
    s.mu.RLock()
    cfg := s.cfg
    s.mu.RUnlock()

    w.Header().Set("Content-Type", "application/json")
    _ = json.NewEncoder(w).Encode(map[string]any{
        "service": "fm-rds-tx",
        "backend": cfg.Backend.Kind,
        "frequencyMHz": cfg.FM.FrequencyMHz,
        "stereoEnabled": cfg.FM.StereoEnabled,
        "rdsEnabled": cfg.RDS.Enabled,
        "toneLeftHz": cfg.Audio.ToneLeftHz,
        "toneRightHz": cfg.Audio.ToneRightHz,
    })
}

func (s *Server) handleDryRun(w http.ResponseWriter, _ *http.Request) {
    s.mu.RLock()
    cfg := s.cfg
    s.mu.RUnlock()

    w.Header().Set("Content-Type", "application/json")
    _ = json.NewEncoder(w).Encode(drypkg.Generate(cfg))
}

func (s *Server) handleConfig(w http.ResponseWriter, r *http.Request) {
    switch r.Method {
    case http.MethodGet:
        s.mu.RLock()
        cfg := s.cfg
        s.mu.RUnlock()
        w.Header().Set("Content-Type", "application/json")
        _ = json.NewEncoder(w).Encode(cfg)
    case http.MethodPost:
        var patch ConfigPatch
        if err := json.NewDecoder(r.Body).Decode(&patch); err != nil {
            http.Error(w, err.Error(), http.StatusBadRequest)
            return
        }

        s.mu.Lock()
        next := s.cfg
        if patch.FrequencyMHz != nil {
            next.FM.FrequencyMHz = *patch.FrequencyMHz
        }
        if patch.OutputDrive != nil {
            next.FM.OutputDrive = *patch.OutputDrive
        }
        if patch.ToneLeftHz != nil {
            next.Audio.ToneLeftHz = *patch.ToneLeftHz
        }
        if patch.ToneRightHz != nil {
            next.Audio.ToneRightHz = *patch.ToneRightHz
        }
        if patch.ToneAmplitude != nil {
            next.Audio.ToneAmplitude = *patch.ToneAmplitude
        }
        if patch.PS != nil {
            next.RDS.PS = *patch.PS
        }
        if patch.RadioText != nil {
            next.RDS.RadioText = *patch.RadioText
        }
        if err := next.Validate(); err != nil {
            s.mu.Unlock()
            http.Error(w, err.Error(), http.StatusBadRequest)
            return
        }
        s.cfg = next
        s.mu.Unlock()

        w.Header().Set("Content-Type", "application/json")
        _ = json.NewEncoder(w).Encode(map[string]any{"ok": true})
    default:
        http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
    }
}