// Package config loads the archivdms application configuration from a YAML
// file. The structure mirrors the archivmail config pattern (Server/Database/
// API/SMTPOut/Audit sections) but drops everything mail-specific (IMAP/POP3/
// SMTP daemon, index backend, etc.) since archivdms is a document-centric DMS.
package config

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"gopkg.in/yaml.v3"
)

// APIConfig holds configuration for the HTTP API server.
type APIConfig struct {
	Bind string `yaml:"bind"`
	// Secret is the master secret from which the JWT signing key is derived.
	Secret string `yaml:"secret"`
	// SecureCookies sets the Secure flag on session cookies. Enable when TLS is
	// terminated at this server or at a trusted reverse proxy.
	SecureCookies bool `yaml:"secure_cookies"`
	// TrustedProxies is a list of IP addresses or CIDR ranges whose
	// X-Forwarded-For header is trusted. Empty = trust no proxy.
	TrustedProxies []string `yaml:"trusted_proxies"`
	// MetricsAllowedIPs sind zusätzliche Quell-IPs oder CIDR-Bereiche, die den
	// unauthentifizierten Prometheus-Endpunkt GET /metrics scrapen dürfen
	// (FDN-08). Loopback ist immer erlaubt, alles andere per Default gesperrt.
	MetricsAllowedIPs []string `yaml:"metrics_allowed_ips"`
}

// ServerConfig holds general server settings.
type ServerConfig struct {
	FQDN    string `yaml:"fqdn"` // used for generated links (invite/reset mails)
	APIPort int    `yaml:"api_port"`
}

// DatabaseConfig holds PostgreSQL connection settings.
type DatabaseConfig struct {
	Host     string `yaml:"host"`
	Port     int    `yaml:"port"`
	Name     string `yaml:"name"`
	User     string `yaml:"user"`
	Password string `yaml:"password"`
	SSLMode  string `yaml:"sslmode"`
}

// DSN builds a PostgreSQL connection string from the config fields.
func (d DatabaseConfig) DSN() string {
	return fmt.Sprintf("postgres://%s:%s@%s:%d/%s?sslmode=%s",
		d.User, d.Password, d.Host, d.Port, d.Name, d.SSLMode)
}

// SMTPOutConfig holds settings for outgoing transactional email (invites,
// password reset, reminder notifications).
type SMTPOutConfig struct {
	Host     string `yaml:"host"`
	Port     int    `yaml:"port"`
	User     string `yaml:"user"`
	Password string `yaml:"password"`
	TLS      bool   `yaml:"tls"`
	From     string `yaml:"from"` // e.g. "archivdms <noreply@firma.de>"
}

// DefaultAuditLogPath is the default location of the append-only JSON-Lines
// audit log file when audit.log_path is not configured.
const DefaultAuditLogPath = "/var/log/archivdms/audit.log"

// AuditConfig holds audit log settings.
type AuditConfig struct {
	LogPath       string `yaml:"log_path"`
	RetentionDays int    `yaml:"retention_days"`
}

// ResolvedLogPath returns the configured audit log file path, falling back to
// DefaultAuditLogPath when unset.
func (a AuditConfig) ResolvedLogPath() string {
	if strings.TrimSpace(a.LogPath) == "" {
		return DefaultAuditLogPath
	}
	return a.LogPath
}

// LoggingConfig holds application logging settings.
type LoggingConfig struct {
	Path  string `yaml:"path"`
	Level string `yaml:"level"`
}

// StorageConfig holds settings for document blob storage on disk.
//
// Layout under BasePath (see internal/ocr and internal/api upload handler):
//
//	<BasePath>/inbox/<tenant_id>/<uuid>.<ext>               raw upload, pre-processing
//	<BasePath>/store/<tenant_id>/<yyyy>/<mm>/<sha256>.<ext>  finished archive (WORM, 0440)
//	<BasePath>/ocr-tmp/<uuid>/                               pdftoppm scratch, removed after use
type StorageConfig struct {
	// BasePath is the root directory for inbox/store/ocr-tmp (see helper
	// methods below). Replaces the old, unused StorePath/store_path field.
	BasePath string `yaml:"base_path"`
	// RetentionDays is the default GoBD retention period (days) applied to new
	// documents when no explicit retain_until is given. 0 = no default lock.
	RetentionDays int `yaml:"retention_days"`
	// MaxUploadSizeMB caps the accepted multipart upload size. 0 = default 50.
	MaxUploadSizeMB int `yaml:"max_upload_size_mb"`
	// SignedURLTTLMinutes is the default validity of signed download URLs
	// (internal/objectstore). 0 = default 15 minutes.
	SignedURLTTLMinutes int `yaml:"signed_url_ttl_minutes"`
}

// ResolvedSignedURLTTL returns the configured signed-download-URL validity,
// falling back to 15 minutes when unset (<= 0).
func (s StorageConfig) ResolvedSignedURLTTL() time.Duration {
	if s.SignedURLTTLMinutes <= 0 {
		return 15 * time.Minute
	}
	return time.Duration(s.SignedURLTTLMinutes) * time.Minute
}

// InboxPath returns the directory raw uploads are written to before hashing
// and OCR processing.
func (s StorageConfig) InboxPath() string { return filepath.Join(s.BasePath, "inbox") }

// StorePath returns the directory the finished, content-addressed WORM
// archive lives in.
func (s StorageConfig) StorePath() string { return filepath.Join(s.BasePath, "store") }

// OCRTmpPath returns the scratch directory for pdftoppm intermediate images.
func (s StorageConfig) OCRTmpPath() string { return filepath.Join(s.BasePath, "ocr-tmp") }

// ThumbnailPath returns the directory holding derived preview thumbnails.
// Thumbnails are regenerable artefacts (not WORM): they may be deleted at any
// time and are re-created lazily on next request. Layout mirrors the store:
// thumbnails/<tenant_id>/<content_hash>.png.
func (s StorageConfig) ThumbnailPath() string { return filepath.Join(s.BasePath, "thumbnails") }

// ResolvedMaxUploadSizeMB returns MaxUploadSizeMB, falling back to a default
// of 50 MB when unset (<= 0).
func (s StorageConfig) ResolvedMaxUploadSizeMB() int {
	if s.MaxUploadSizeMB <= 0 {
		return 50
	}
	return s.MaxUploadSizeMB
}

// OCRConfig holds settings for the tesseract/poppler-utils OCR sidecar
// pipeline (internal/ocr). All binaries are optional system packages — a
// missing binary degrades OCR to a no-op rather than failing the upload.
type OCRConfig struct {
	// TesseractPath is the path/name of the tesseract binary. Default "tesseract".
	TesseractPath string `yaml:"tesseract_path"`
	// PdftoppmPath is the path/name of the pdftoppm binary. Default "pdftoppm".
	PdftoppmPath string `yaml:"pdftoppm_path"`
	// Languages is the tesseract -l argument, e.g. "deu+eng". Default "deu+eng".
	Languages string `yaml:"languages"`
	// TimeoutSeconds bounds each individual OCR subprocess call. Default 60.
	TimeoutSeconds int `yaml:"timeout_seconds"`
	// SofficePath is the path/name of the LibreOffice headless binary used to
	// convert Office documents (docx/xlsx/pptx/odt/...) to PDF before OCR.
	// Default "soffice". A missing binary degrades Office ingest to a no-op.
	SofficePath string `yaml:"soffice_path"`
	// BinarizeOCR enables an Otsu auto-threshold (black/white) step at the end
	// of the image preprocessing pipeline (internal/ocr.Extractor.Binarize),
	// after deskew/contrast-normalize/OSD-rotation. Default false: this is a
	// lossy step (every pixel becomes pure black or white) that helps flat
	// text scans but can hurt documents with color stamps/signatures or
	// embedded photos — enable per-deployment only after validating against
	// that corpus. Requires ImageMagick 7 (`-auto-threshold` syntax); a
	// missing/older convert binary just skips the step (best-effort, same as
	// every other preprocessing step here).
	BinarizeOCR bool `yaml:"binarize_ocr"`
	// DeskewMethod selects the fine-skew-angle correction strategy used in
	// internal/ocr.Extractor.runTesseract before the OSD 90-degree rotation
	// pass. "imagemagick" (default/empty) keeps the existing behavior:
	// ImageMagick's own `-deskew 40%` peak/valley background-projection
	// analysis (internal/ocr.deskewImage). "hough" instead detects the angle
	// via a Python/OpenCV sidecar script (internal/ocr/scripts/
	// hough_deskew.py, minAreaRect/HoughLinesP-based) and applies it with a
	// plain `convert -rotate <deg>` — separating angle detection from angle
	// application, which the ImageMagick approach does not do and which
	// fails on tightly-cropped phone photos lacking background margin.
	// Requires python3 + opencv-python (Debian: python3-opencv) on the host;
	// falls back to no-op (angle 0, same as any other best-effort
	// preprocessing step here) if the script/dependency is missing.
	DeskewMethod string `yaml:"deskew_method"`
	// HoughDeskewScriptPath overrides the path to hough_deskew.py. Empty
	// defaults to "/opt/archivdms/scripts/hough_deskew.py" (the on-premise
	// install layout — see install.sh/update.sh, INSTALL_DIR=/opt/archivdms).
	// Only consulted when DeskewMethod == "hough".
	HoughDeskewScriptPath string `yaml:"hough_deskew_script_path"`
}

// ResolvedTesseractPath returns TesseractPath, defaulting to "tesseract".
func (o OCRConfig) ResolvedTesseractPath() string {
	if strings.TrimSpace(o.TesseractPath) == "" {
		return "tesseract"
	}
	return o.TesseractPath
}

// ResolvedPdftoppmPath returns PdftoppmPath, defaulting to "pdftoppm".
func (o OCRConfig) ResolvedPdftoppmPath() string {
	if strings.TrimSpace(o.PdftoppmPath) == "" {
		return "pdftoppm"
	}
	return o.PdftoppmPath
}

// ResolvedSofficePath returns SofficePath, defaulting to "soffice".
func (o OCRConfig) ResolvedSofficePath() string {
	if strings.TrimSpace(o.SofficePath) == "" {
		return "soffice"
	}
	return o.SofficePath
}

// ResolvedDeskewMethod returns DeskewMethod, defaulting to "imagemagick"
// (the pre-existing behavior — see the DeskewMethod field doc). Any value
// other than "hough" is treated as "imagemagick" so a typo in config.yaml
// degrades to the known-safe default rather than silently disabling deskew.
func (o OCRConfig) ResolvedDeskewMethod() string {
	if strings.TrimSpace(strings.ToLower(o.DeskewMethod)) == "hough" {
		return "hough"
	}
	return "imagemagick"
}

// ResolvedHoughDeskewScriptPath returns HoughDeskewScriptPath, defaulting to
// "/opt/archivdms/scripts/hough_deskew.py" (see the field doc).
func (o OCRConfig) ResolvedHoughDeskewScriptPath() string {
	if strings.TrimSpace(o.HoughDeskewScriptPath) == "" {
		return "/opt/archivdms/scripts/hough_deskew.py"
	}
	return o.HoughDeskewScriptPath
}

// ResolvedLanguages returns Languages, defaulting to "deu+eng".
func (o OCRConfig) ResolvedLanguages() string {
	if strings.TrimSpace(o.Languages) == "" {
		return "deu+eng"
	}
	return o.Languages
}

// ResolvedTimeout returns TimeoutSeconds as a time.Duration, defaulting to 60s.
func (o OCRConfig) ResolvedTimeout() time.Duration {
	if o.TimeoutSeconds <= 0 {
		return 60 * time.Second
	}
	return time.Duration(o.TimeoutSeconds) * time.Second
}

// SFTPConfig holds settings for the embedded per-tenant SFTP server
// (internal/sftpserver). Disabled by default — no port is opened unless
// explicitly enabled.
type SFTPConfig struct {
	// Enabled turns the embedded SFTP server on/off. Default false.
	Enabled bool `yaml:"enabled"`
	// Bind is the listen address, e.g. ":2222".
	Bind string `yaml:"bind"`
	// HostKeyPath is where the server's SSH host key is persisted. Generated
	// on first start if missing. Defaults to "<storage.base_path>/.ssh/host_key".
	HostKeyPath string `yaml:"host_key_path"`
}

// ResolvedBind returns Bind, defaulting to ":2222".
func (c SFTPConfig) ResolvedBind() string {
	if strings.TrimSpace(c.Bind) == "" {
		return ":2222"
	}
	return c.Bind
}

// ResolvedHostKeyPath returns HostKeyPath, defaulting to
// "<basePath>/.ssh/host_key" when unset.
func (c SFTPConfig) ResolvedHostKeyPath(basePath string) string {
	if strings.TrimSpace(c.HostKeyPath) != "" {
		return c.HostKeyPath
	}
	return filepath.Join(basePath, ".ssh", "host_key")
}

// IndexConfig holds settings for the optional full-text search index
// (internal/index, Manticore Search over the MySQL protocol, port 9306).
//
// Phase 1 wires only the write/sync layer — there is no search endpoint yet.
// When ManticoreDSN is empty the index is disabled entirely: the store's
// Indexer stays nil and every sync call is a silent no-op (Postgres remains the
// single source of truth).
type IndexConfig struct {
	// ManticoreDSN is a go-sql-driver/mysql DSN pointing at Manticore's SQL
	// port, e.g. "archivdms@tcp(127.0.0.1:9306)/?charset=utf8mb4". Empty =
	// index disabled.
	ManticoreDSN string `yaml:"manticore_dsn"`
}

// JobQueueConfig holds settings for the tenant-fair, Postgres-backed
// processing queue (internal/jobqueue): OCR extraction, taxonomy
// auto-assignment and on_upload workflows run asynchronously in worker
// goroutines inside this same process (no separate service/container).
//
// All fields are optional — the defaults below are tuned for a single
// mid-sized server running Tesseract locally.
type JobQueueConfig struct {
	// Disabled turns the async pipeline off entirely. Documents then stay in
	// processing_status='queued' until the queue is enabled again (nothing is
	// lost — the WORM file and the job row are already persisted). Default
	// false, i.e. the queue runs.
	Disabled bool `yaml:"disabled"`
	// Workers is the number of concurrent worker goroutines. Default 2 —
	// Tesseract is CPU-bound, more workers than cores hurts.
	Workers int `yaml:"workers"`
	// PollIntervalMS is how often the dispatcher looks for due jobs.
	// Default 2000 (2s).
	PollIntervalMS int `yaml:"poll_interval_ms"`
	// JobTimeoutSeconds bounds one job run and doubles as the reaper's
	// threshold for stuck 'processing' rows. Default 600 (10 min) — large
	// multi-page scans plus LibreOffice conversion can legitimately take
	// minutes.
	JobTimeoutSeconds int `yaml:"job_timeout_seconds"`
	// MaxRetries is the retry_count cap. Once exceeded, the job stays
	// permanently 'failed' and is only retried on explicit manual request.
	// Default 5.
	MaxRetries int `yaml:"max_retries"`
}

// ResolvedWorkers returns Workers, defaulting to 2.
func (j JobQueueConfig) ResolvedWorkers() int {
	if j.Workers <= 0 {
		return 2
	}
	return j.Workers
}

// ResolvedPollInterval returns PollIntervalMS as a Duration, default 2s.
func (j JobQueueConfig) ResolvedPollInterval() time.Duration {
	if j.PollIntervalMS <= 0 {
		return 2 * time.Second
	}
	return time.Duration(j.PollIntervalMS) * time.Millisecond
}

// ResolvedJobTimeout returns JobTimeoutSeconds as a Duration, default 10min.
func (j JobQueueConfig) ResolvedJobTimeout() time.Duration {
	if j.JobTimeoutSeconds <= 0 {
		return 10 * time.Minute
	}
	return time.Duration(j.JobTimeoutSeconds) * time.Second
}

// ResolvedMaxRetries returns MaxRetries, defaulting to 5.
func (j JobQueueConfig) ResolvedMaxRetries() int {
	if j.MaxRetries <= 0 {
		return 5
	}
	return j.MaxRetries
}

// PageSplitConfig holds settings for barcode separator-page splitting at
// ingest (internal/pagesplit). A printed separator sheet carrying the
// configured barcode cuts a multi-page PDF scan into several individual
// documents; the separator page itself is discarded.
//
// Deliberately disabled by default and configured globally (config.yaml)
// rather than per tenant for now: this is the first iteration, and the
// project rule for new preprocessing behaviour is to introduce it
// conservatively and validate it in the field before turning it on broadly
// (same approach as ocr.binarize_ocr). A per-tenant setting plus a settings UI
// is the intended next step.
type PageSplitConfig struct {
	// Enabled turns separator-page splitting on. Default false.
	Enabled bool `yaml:"enabled"`
	// Marker is the barcode payload identifying a separator page. Empty
	// defaults to pagesplit.DefaultMarker ("ARCHIVDMS-SPLIT"). Matched
	// case-insensitively after trimming.
	Marker string `yaml:"marker"`
	// MarkerPrefix switches matching from equality to prefix matching, so a
	// separator sheet may carry additional payload after the marker.
	MarkerPrefix bool `yaml:"marker_prefix"`
	// RasterDPI is the resolution separator detection rasterizes pages at.
	// 0 = default 150 (enough for a full-page separator barcode, far cheaper
	// than the 300 dpi OCR pass).
	RasterDPI int `yaml:"raster_dpi"`
	// MaxPages caps how many pages are analysed; longer documents are archived
	// unsplit. 0 = default 200.
	MaxPages int `yaml:"max_pages"`
	// TimeoutSeconds bounds each poppler subprocess call. 0 = default 120.
	TimeoutSeconds int `yaml:"timeout_seconds"`
}

// Config is the full application configuration loaded from YAML.
type Config struct {
	Server    ServerConfig    `yaml:"server"`
	Storage   StorageConfig   `yaml:"storage"`
	OCR       OCRConfig       `yaml:"ocr"`
	PageSplit PageSplitConfig `yaml:"pagesplit"`
	JobQueue  JobQueueConfig  `yaml:"jobqueue"`
	SFTP      SFTPConfig      `yaml:"sftp"`
	Index     IndexConfig     `yaml:"index"`
	Database  DatabaseConfig  `yaml:"database"`
	SMTPOut   SMTPOutConfig   `yaml:"smtp_out"`
	API       APIConfig       `yaml:"api"`
	Audit     AuditConfig     `yaml:"audit"`
	Logging   LoggingConfig   `yaml:"logging"`
}

// Load reads a YAML config file from path and returns a parsed Config.
// It also bootstraps the storage directory tree (inbox/store/ocr-tmp) so the
// upload handler and OCR pipeline can rely on it existing at startup.
func Load(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	var cfg Config
	if err := yaml.Unmarshal(data, &cfg); err != nil {
		return nil, err
	}

	if cfg.Storage.BasePath != "" {
		for _, dir := range []string{cfg.Storage.InboxPath(), cfg.Storage.StorePath(), cfg.Storage.OCRTmpPath(), cfg.Storage.ThumbnailPath()} {
			if err := os.MkdirAll(dir, 0o750); err != nil {
				return nil, fmt.Errorf("config: create storage dir %s: %w", dir, err)
			}
		}
	}

	return &cfg, nil
}