package main

import (
	"database/sql"
	"fmt"
	"os"

	_ "github.com/mattn/go-sqlite3"
)

// OpenDB opens or creates the SQLite database and applies the schema.
func OpenDB(dbPath, schemaPath string) (*sql.DB, error) {
	db, err := sql.Open("sqlite3", dbPath+"?_journal_mode=WAL&_foreign_keys=ON")
	if err != nil {
		return nil, fmt.Errorf("opening database: %w", err)
	}

	schema, err := os.ReadFile(schemaPath)
	if err != nil {
		return nil, fmt.Errorf("reading schema: %w", err)
	}

	if _, err := db.Exec(string(schema)); err != nil {
		return nil, fmt.Errorf("applying schema: %w", err)
	}

	return db, nil
}

// DBWriter writes analysis results to the SQLite database.
type DBWriter struct {
	db *sql.DB
}

// NewDBWriter creates a new DBWriter.
func NewDBWriter(db *sql.DB) *DBWriter {
	return &DBWriter{db: db}
}

// WriteAll writes all analysis results to the database in a single transaction.
func (w *DBWriter) WriteAll(result *AnalysisResult) error {
	tx, err := w.db.Begin()
	if err != nil {
		return fmt.Errorf("beginning transaction: %w", err)
	}
	defer tx.Rollback()

	moduleIDs := make(map[string]int64)
	featureIDs := make(map[string]int64)

	for _, mod := range result.Modules {
		modID, err := w.insertModule(tx, &mod)
		if err != nil {
			return fmt.Errorf("inserting module %s: %w", mod.Name, err)
		}
		moduleIDs[mod.Name] = modID

		for _, feat := range mod.Features {
			featID, err := w.insertFeature(tx, modID, &feat)
			if err != nil {
				return fmt.Errorf("inserting feature %s: %w", feat.Name, err)
			}
			featureIDs[mod.Name+":"+feat.Name] = featID
		}

		for _, test := range mod.Tests {
			var featureID *int64
			if test.FeatureName != "" {
				if fid, ok := featureIDs[mod.Name+":"+test.FeatureName]; ok {
					featureID = &fid
				}
			}
			if err := w.insertTest(tx, modID, featureID, &test); err != nil {
				return fmt.Errorf("inserting test %s: %w", test.Name, err)
			}
		}
	}

	for _, dep := range result.Dependencies {
		sourceID, ok := moduleIDs[dep.SourceModule]
		if !ok {
			continue
		}
		targetID, ok := moduleIDs[dep.TargetModule]
		if !ok {
			continue
		}
		if err := w.insertDependency(tx, "module", sourceID, "module", targetID, dep.DependencyKind); err != nil {
			return fmt.Errorf("inserting dependency %s->%s: %w", dep.SourceModule, dep.TargetModule, err)
		}
	}

	for _, imp := range result.Imports {
		if imp.IsStdlib {
			continue
		}
		if err := w.insertLibrary(tx, &imp); err != nil {
			return fmt.Errorf("inserting library %s: %w", imp.ImportPath, err)
		}
	}

	return tx.Commit()
}

func (w *DBWriter) insertModule(tx *sql.Tx, mod *Module) (int64, error) {
	res, err := tx.Exec(
		`INSERT INTO modules (name, description, go_package, go_file, go_line_count, status)
		 VALUES (?, ?, ?, ?, ?, 'not_started')`,
		mod.Name, mod.Description, mod.GoPackage, mod.GoFile, mod.GoLineCount,
	)
	if err != nil {
		return 0, err
	}
	return res.LastInsertId()
}

func (w *DBWriter) insertFeature(tx *sql.Tx, moduleID int64, feat *Feature) (int64, error) {
	res, err := tx.Exec(
		`INSERT INTO features (module_id, name, description, go_file, go_class, go_method, go_line_number, go_line_count, status)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, 'not_started')`,
		moduleID, feat.Name, feat.Description, feat.GoFile, feat.GoClass, feat.GoMethod, feat.GoLineNumber, feat.GoLineCount,
	)
	if err != nil {
		return 0, err
	}
	return res.LastInsertId()
}

func (w *DBWriter) insertTest(tx *sql.Tx, moduleID int64, featureID *int64, test *TestFunc) error {
	_, err := tx.Exec(
		`INSERT INTO unit_tests (module_id, feature_id, name, description, go_file, go_class, go_method, go_line_number, go_line_count, status)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, 'not_started')`,
		moduleID, featureID, test.Name, test.Description, test.GoFile, test.GoClass, test.GoMethod, test.GoLineNumber, test.GoLineCount,
	)
	return err
}

func (w *DBWriter) insertDependency(tx *sql.Tx, srcType string, srcID int64, tgtType string, tgtID int64, kind string) error {
	_, err := tx.Exec(
		`INSERT OR IGNORE INTO dependencies (source_type, source_id, target_type, target_id, dependency_kind)
		 VALUES (?, ?, ?, ?, ?)`,
		srcType, srcID, tgtType, tgtID, kind,
	)
	return err
}

func (w *DBWriter) insertLibrary(tx *sql.Tx, imp *ImportInfo) error {
	_, err := tx.Exec(
		`INSERT OR IGNORE INTO library_mappings (go_import_path, go_library_name, status)
		 VALUES (?, ?, 'not_mapped')`,
		imp.ImportPath, imp.ImportPath,
	)
	return err
}