// Package config loads geniusrund's runtime infrastructure configuration
// from environment variables (paths and process settings that don't belong
// in the user-editable profile). Garmin credentials and every tunable
// analysis-engine parameter live in the profile (internal/store.Profile)
// instead -- see docs/superpowers/specs/2026-07-17-profile-taxonomy-analysis-engine-design.md.
package config

import (
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"
)

// Config holds geniusrund's process-level configuration.
type Config struct {
	// Addr is the HTTP listen address, e.g. ":8080".
	Addr string
	// DBPath is the SQLite database file path.
	DBPath string

	// GarminPythonPath is the python3 interpreter used to run the embedded
	// Garmin wrapper script (internal/garmin's go:embed'd wrapper.py).
	// Defaults to "python3" resolved via PATH if unset.
	GarminPythonPath string
	// GarminTokenStoreRoot is the root directory under which each user's
	// Garmin session cache lives (one subdirectory per user id, e.g.
	// "<root>/3"). Read from the GARMIN_TOKENSTORE env var; if unset, it
	// defaults to a "garmin-tokenstores" directory next to DBPath so every
	// deployment gets per-user isolation automatically -- multi-tenant
	// operation always relies on this being a real, distinct-per-user path
	// (see api.Server.garminFor), so it can never be silently left empty.
	GarminTokenStoreRoot string

	MinConfidence        float64
	IncrementalSyncEvery time.Duration
	// LogLevel controls internal/applog's JSON logger ("debug"|"info"|"warn"|"error").
	LogLevel string

	// OIDC login gate (Keycloak). BackendURL is this app's own externally
	// reachable origin (e.g. "https://geniusrun.example.com") -- it derives
	// OIDCRedirectURL and whether session cookies can be marked Secure,
	// instead of requiring both to be configured separately and risking them
	// drifting out of sync.
	BackendURL string
	// FrontendURL is the origin the browser should land on after the OIDC
	// callback (both success and failure) -- e.g. "http://localhost:5173" in
	// local dev, where the frontend and backend are different origins
	// bridged by CORS (see internal/api's corsMiddleware and
	// frontend/src/api/client.ts's BASE_URL). Defaults to BackendURL when
	// unset, which is correct for the common production topology where a
	// reverse proxy unifies frontend and backend under one origin.
	// BackendURL itself must stay pointed at the backend's own origin
	// regardless -- it derives OIDCRedirectURL and post_logout_redirect_uri,
	// which must match wherever those routes are actually served.
	FrontendURL      string
	OIDCIssuerURL    string
	OIDCClientID     string
	OIDCClientSecret string
	OIDCRedirectURL  string
	OIDCRequiredRole string
	SessionSecret    []byte
	SessionDuration  time.Duration
	SessionSecure    bool
}

// Load reads configuration from environment variables, applying defaults
// for anything optional. Returns an error if a required variable is unset.
func Load() (Config, error) {
	cfg := Config{
		Addr:                 getEnvDefault("GENIUSRUN_ADDR", ":8080"),
		DBPath:               getEnvDefault("GENIUSRUN_DB_PATH", "geniusrun.db"),
		GarminPythonPath:     getEnvDefault("GARMIN_WRAPPER_PYTHON", "python3"),
		GarminTokenStoreRoot: os.Getenv("GARMIN_TOKENSTORE"),
		MinConfidence:        getEnvFloat("GENIUSRUN_MIN_CONFIDENCE", 0.6),
		IncrementalSyncEvery: getEnvDuration("GENIUSRUN_INCREMENTAL_SYNC_EVERY", 6*time.Hour),
		LogLevel:             getEnvDefault("GENIUSRUN_LOG_LEVEL", "info"),
		BackendURL:           strings.TrimRight(os.Getenv("GENIUSRUN_BACKEND_URL"), "/"),
		OIDCIssuerURL:        os.Getenv("GENIUSRUN_OIDC_ISSUER_URL"),
		OIDCClientID:         os.Getenv("GENIUSRUN_OIDC_CLIENT_ID"),
		OIDCClientSecret:     os.Getenv("GENIUSRUN_OIDC_CLIENT_SECRET"),
		OIDCRequiredRole:     getEnvDefault("GENIUSRUN_OIDC_REQUIRED_ROLE", "geniusrun-user"),
		SessionDuration:      getEnvDuration("GENIUSRUN_SESSION_DURATION", 720*time.Hour),
	}

	if cfg.GarminTokenStoreRoot == "" {
		cfg.GarminTokenStoreRoot = filepath.Join(filepath.Dir(cfg.DBPath), "garmin-tokenstores")
		log.Printf("GARMIN_TOKENSTORE not set, defaulting to %q", cfg.GarminTokenStoreRoot)
	}

	if cfg.BackendURL == "" {
		return cfg, fmt.Errorf("GENIUSRUN_BACKEND_URL is required (e.g. https://geniusrun.example.com)")
	}
	cfg.FrontendURL = strings.TrimRight(getEnvDefault("GENIUSRUN_FRONTEND_URL", cfg.BackendURL), "/")
	if cfg.OIDCIssuerURL == "" {
		return cfg, fmt.Errorf("GENIUSRUN_OIDC_ISSUER_URL is required")
	}
	if cfg.OIDCClientID == "" {
		return cfg, fmt.Errorf("GENIUSRUN_OIDC_CLIENT_ID is required")
	}
	if cfg.OIDCClientSecret == "" {
		return cfg, fmt.Errorf("GENIUSRUN_OIDC_CLIENT_SECRET is required")
	}
	sessionSecret := os.Getenv("GENIUSRUN_SESSION_SECRET")
	if len(sessionSecret) < 32 {
		return cfg, fmt.Errorf("GENIUSRUN_SESSION_SECRET is required and must be at least 32 characters")
	}
	cfg.SessionSecret = []byte(sessionSecret)
	cfg.OIDCRedirectURL = cfg.BackendURL + "/api/session/callback"
	cfg.SessionSecure = strings.HasPrefix(cfg.BackendURL, "https://")

	return cfg, nil
}

func getEnvDefault(key, def string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return def
}

func getEnvFloat(key string, def float64) float64 {
	if v := os.Getenv(key); v != "" {
		if f, err := strconv.ParseFloat(v, 64); err == nil {
			return f
		}
	}
	return def
}

func getEnvDuration(key string, def time.Duration) time.Duration {
	if v := os.Getenv(key); v != "" {
		if d, err := time.ParseDuration(v); err == nil {
			return d
		}
	}
	return def
}