// 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 mcp-garmin's venv python executable.
	GarminPythonPath string
	// GarminServerPath is mcp-garmin's server.py.
	GarminServerPath string
	// GarminTokenStoreRoot is the root directory under which each user's
	// mcp-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

	// OIDC login gate (Keycloak). PublicBaseURL 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.
	PublicBaseURL    string
	OIDCIssuerURL    string
	OIDCClientID     string
	OIDCClientSecret string
	OIDCRedirectURL  string
	OIDCRequiredRole string
	SessionSecret    []byte
	SessionDuration  time.Duration
	SessionSecure    bool

	// LegacyOwnerOIDCSub, if set, is used exactly once at startup (via
	// store.ClaimLegacyOwner) to bind this deployment's pre-existing
	// single-tenant data to one named OIDC subject after upgrading to
	// per-user profiles. Safe to leave set indefinitely -- ClaimLegacyOwner
	// no-ops once any user already exists.
	LegacyOwnerOIDCSub string
}

// 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:     os.Getenv("MCP_GARMIN_PYTHON"),
		GarminServerPath:     os.Getenv("MCP_GARMIN_SERVER"),
		GarminTokenStoreRoot: os.Getenv("GARMIN_TOKENSTORE"),
		MinConfidence:        getEnvFloat("GENIUSRUN_MIN_CONFIDENCE", 0.6),
		IncrementalSyncEvery: getEnvDuration("GENIUSRUN_INCREMENTAL_SYNC_EVERY", 6*time.Hour),
		PublicBaseURL:        strings.TrimRight(os.Getenv("GENIUSRUN_PUBLIC_BASE_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),
		LegacyOwnerOIDCSub:   os.Getenv("GENIUSRUN_LEGACY_OWNER_OIDC_SUB"),
	}

	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.GarminPythonPath == "" {
		return cfg, fmt.Errorf("MCP_GARMIN_PYTHON is required (path to mcp-garmin's venv python)")
	}
	if cfg.GarminServerPath == "" {
		return cfg, fmt.Errorf("MCP_GARMIN_SERVER is required (path to mcp-garmin's server.py)")
	}
	if cfg.PublicBaseURL == "" {
		return cfg, fmt.Errorf("GENIUSRUN_PUBLIC_BASE_URL is required (e.g. https://geniusrun.example.com)")
	}
	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.PublicBaseURL + "/api/session/callback"
	cfg.SessionSecure = strings.HasPrefix(cfg.PublicBaseURL, "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
}