package kjv

import (
	"database/sql"
	"fmt"
	"io/fs"
	"os"
	"path"
	"path/filepath"
	"strings"
)

// Everything the program serves or reads besides the Bible itself (pages,
// scripts, styles, the 1828 dictionary, word lists) lives in the assets table
// of the companion database, so the program and the database are the only two
// files that need to be distributed.

var assetMIME = map[string]string{
	".html": "text/html; charset=utf-8",
	".css":  "text/css; charset=utf-8",
	".js":   "application/javascript; charset=utf-8",
	".json": "application/json",
	".svg":  "image/svg+xml",
	".dic":  "text/plain; charset=utf-8",
	".aff":  "text/plain; charset=utf-8",
}

func isAssetFile(rel string) bool {
	dir := path.Dir(rel)
	switch {
	case rel == "kjv_fe.html":
		return true
	case dir == "html", dir == "js", dir == "static":
		return true
	case dir == "styles":
		return strings.HasSuffix(rel, ".css")
	case dir == "data":
		ext := path.Ext(rel)
		return ext == ".json" || ext == ".dic" || ext == ".aff"
	}
	return false
}

// ImportAssets replaces the assets table with the files of a source checkout.
func ImportAssets(dbPath, srcDir string) error {
	db, err := sql.Open("sqlite", "file:"+dbPath+"?_pragma=busy_timeout(5000)")
	if err != nil {
		return err
	}
	defer db.Close()
	tx, err := db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	for _, stmt := range []string{
		"CREATE TABLE IF NOT EXISTS assets (path TEXT PRIMARY KEY, mime TEXT NOT NULL, body BLOB NOT NULL)",
		"DELETE FROM assets",
	} {
		if _, err := tx.Exec(stmt); err != nil {
			return err
		}
	}
	n := 0
	err = filepath.WalkDir(srcDir, func(p string, d fs.DirEntry, err error) error {
		if err != nil || !d.Type().IsRegular() { // no directories, and never follow a symlink out of the tree
			return err
		}
		rel, _ := filepath.Rel(srcDir, p)
		rel = filepath.ToSlash(rel)
		if !isAssetFile(rel) {
			return nil
		}
		body, err := os.ReadFile(p)
		if err != nil {
			return err
		}
		mime := assetMIME[path.Ext(rel)]
		if mime == "" {
			mime = "application/octet-stream"
		}
		n++
		_, err = tx.Exec("INSERT INTO assets (path, mime, body) VALUES (?, ?, ?)", rel, mime, body)
		return err
	})
	if err != nil {
		return err
	}
	if n == 0 {
		return fmt.Errorf("no assets found under %s (expected html/, js/, styles/, data/*.json ...)", srcDir)
	}
	fmt.Printf("imported %d assets into %s\n", n, dbPath)
	return tx.Commit()
}

// LoadAssets reads every asset into memory.
func (s *Store) LoadAssets() (map[string][]byte, error) {
	rows, err := s.db.Query("SELECT path, body FROM assets")
	if err != nil {
		return nil, fmt.Errorf("no assets table (run: kjv-api import-assets <source dir>): %w", err)
	}
	defer rows.Close()
	out := map[string][]byte{}
	for rows.Next() {
		var p string
		var b []byte
		if err := rows.Scan(&p, &b); err != nil {
			return nil, err
		}
		out[p] = b
	}
	return out, rows.Err()
}