postgres migrations

.gitignore

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+.idea

go.mod

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+module ewintr.nl/yogai
+
+go 1.20
+
+require github.com/lib/pq v1.10.9

go.sum

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+github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=
+github.com/lib/pq v1.10.9/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=

prompts.txt

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+I would like a 25 minute yoga flow to stretch.
+
+I would like a yoga practice especially to sooth the low back. Preferably all standing.
+
+I would like a yin yoga practice about 1 hour long, using no props, except maybe one block and/or a bolster. Specifically dedicated to relax the body. But without deep stretching.
+
+I would like a yoga nidra practice. No longer than 30 minutes, but no shorter than 20 minutes.
+
+I would like a yoga flow between 35 and 45 minutes, without downward facing dogs. Focus on heart opening and back bends.
+
+Give me an easy morning yoga flowto energize. No more than 20 minutes. I like the practices of Well with Hels, but an other yoga teacher might be good as well.
+
+I have terrible upper back pain. Can you recommend a yoga practice to combat that? Preferably all low to the ground.
+
+What yoga practice can you recommend to combatting the after lunch dip? Please no more than 15 minutes and all standing.
+
+I am very tired at the moment. I would like to practice some yoga to energize, but not to strenuous. I have about an hour to spare.
+
+Can you give me a yoga practice in which I can practice the yogi squat? Doesn’t have to be a tutorial, preferably a practice with other poses.
+
+I’m very restless. Can you find me a yoga practice to calm down? I prefer some movement in it, I don’t want to ly still most of the time.
+

service.go

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+package main
+
+import (
+	"database/sql"
+	"ewintr.nl/yogai/storage"
+	"fmt"
+	"os"
+)
+
+func main() {
+	pgInfo := struct {
+		Host     string
+		Port     string
+		User     string
+		Password string
+		Database string
+	}{
+		Host:     getParam("POSTGRES_HOST", "localhost"),
+		Port:     getParam("POSTGRES_PORT", "5432"),
+		User:     getParam("POSTGRES_USER", "yogai"),
+		Password: getParam("POSTGRES_PASSWORD", "yogai"),
+		Database: getParam("POSTGRES_DB", "yogai"),
+	}
+	db, err := sql.Open("postgres", fmt.Sprintf("host=%s port=%s user=%s password=%s dbname=%s sslmode=disable",
+		pgInfo.Host, pgInfo.Port, pgInfo.User, pgInfo.Password, pgInfo.Database))
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	_, err = storage.NewPostgres(db)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+}
+
+func getParam(param, def string) string {
+	if val, ok := os.LookupEnv(param); ok {
+		return val
+	}
+	return def
+}

storage/postgres.go

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+package storage
+
+import (
+	"database/sql"
+	"fmt"
+	_ "github.com/lib/pq"
+)
+
+type Postgres struct {
+	db *sql.DB
+}
+
+func NewPostgres(db *sql.DB) (*Postgres, error) {
+	p := &Postgres{db: db}
+	if err := p.migrate(pgMigration); err != nil {
+		return &Postgres{}, err
+	}
+
+	return p, nil
+}
+
+var pgMigration = []string{
+	`CREATE TABLE channel (
+    id SERIAL PRIMARY KEY,
+    url VARCHAR(255) NOT NULL,
+    feed_url VARCHAR(255) NOT NULL,
+    name VARCHAR(255) NOT NULL
+)`,
+	`CREATE TABLE video (
+    id SERIAL PRIMARY KEY,
+    channel_id INTEGER REFERENCES channel(id) ON DELETE CASCADE,
+    url VARCHAR(255) NOT NULL,
+    title VARCHAR(255) NOT NULL,
+    description TEXT,
+    summary TEXT
+)`,
+}
+
+func (p *Postgres) migrate(wanted []string) error {
+	query := `CREATE TABLE IF NOT EXISTS migration
+("id" SERIAL PRIMARY KEY, "query" TEXT)`
+	_, err := p.db.Exec(query)
+	if err != nil {
+		return err
+	}
+
+	// find existing
+	rows, err := p.db.Query(`SELECT query FROM migration ORDER BY id`)
+	if err != nil {
+		return err
+	}
+
+	existing := []string{}
+	for rows.Next() {
+		var query string
+		if err := rows.Scan(&query); err != nil {
+			return err
+		}
+		existing = append(existing, query)
+	}
+	rows.Close()
+
+	// compare
+	missing, err := compareMigrations(wanted, existing)
+	if err != nil {
+		return err
+	}
+
+	// execute missing
+	for _, query := range missing {
+		if _, err := p.db.Exec(query); err != nil {
+			return err
+		}
+
+		// register
+		if _, err := p.db.Exec(`
+INSERT INTO migration
+(query) VALUES ($1)
+`, query); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func compareMigrations(wanted, existing []string) ([]string, error) {
+	needed := []string{}
+	if len(wanted) < len(existing) {
+		return []string{}, fmt.Errorf("not enough migrations")
+	}
+
+	for i, want := range wanted {
+		switch {
+		case i >= len(existing):
+			needed = append(needed, want)
+		case want == existing[i]:
+			// do nothing
+		case want != existing[i]:
+			return []string{}, fmt.Errorf("incompatible migration: %v", want)
+		}
+	}
+
+	return needed, nil
+}