package db

import (
	"context"
	"database/sql"
	"fmt"
	"log"

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

type DB struct {
	*sql.DB
}

type Execer interface {
	Query(query string, args ...any) (*sql.Rows, error)
	QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error)
	QueryRow(query string, args ...any) *sql.Row
	QueryRowContext(ctx context.Context, query string, args ...any) *sql.Row
	Exec(query string, args ...any) (sql.Result, error)
	ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
	Prepare(query string) (*sql.Stmt, error)
	PrepareContext(ctx context.Context, query string) (*sql.Stmt, error)
}

func Make(dbPath string) (*DB, error) {
	db, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		return nil, err
	}
	_, err = db.Exec(`
		pragma journal_mode = WAL;
		pragma synchronous = normal;
		pragma foreign_keys = on;
		pragma temp_store = memory;
		pragma mmap_size = 30000000000;
		pragma page_size = 32768;
		pragma auto_vacuum = incremental;
		pragma busy_timeout = 5000;

		create table if not exists registrations (
			id integer primary key autoincrement,
			domain text not null unique,
			did text not null,
			secret text not null,
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
			registered text
		);
		create table if not exists public_keys (
			id integer primary key autoincrement,
			did text not null,
			name text not null,
			key text not null,
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
			unique(did, name, key)
		);
		create table if not exists repos (
			id integer primary key autoincrement,
			did text not null,
			name text not null,
			knot text not null,
			rkey text not null,
			at_uri text not null unique,
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
			unique(did, name, knot, rkey)
		);
		create table if not exists collaborators (
			id integer primary key autoincrement,
			did text not null,
			repo integer not null,
			foreign key (repo) references repos(id) on delete cascade
		);
		create table if not exists follows (
			user_did text not null,
			subject_did text not null,
			rkey text not null,
			followed_at text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
			primary key (user_did, subject_did),
			check (user_did <> subject_did)
		);
		create table if not exists issues (
			id integer primary key autoincrement,
			owner_did text not null,
			repo_at text not null,
			issue_id integer not null,
			title text not null,
			body text not null,
			open integer not null default 1,
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
			issue_at text,
			unique(repo_at, issue_id),
			foreign key (repo_at) references repos(at_uri) on delete cascade
		);
		create table if not exists comments (
			id integer primary key autoincrement,
			owner_did text not null,
			issue_id integer not null,
			repo_at text not null,
			comment_id integer not null,
			comment_at text not null,
			body text not null,
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
			unique(issue_id, comment_id),
			foreign key (repo_at, issue_id) references issues(repo_at, issue_id) on delete cascade
		);
		create table if not exists pulls (
			-- identifiers
			id integer primary key autoincrement,
			pull_id integer not null,

			-- at identifiers
			repo_at text not null,
			owner_did text not null,
			rkey text not null,
			pull_at text,

			-- content
			title text not null,
			body text not null,
			target_branch text not null,
			state integer not null default 0 check (state in (0, 1, 2)), -- open, merged, closed

			-- meta
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),

			-- constraints
			unique(repo_at, pull_id),
			foreign key (repo_at) references repos(at_uri) on delete cascade
		);

		-- every pull must have atleast 1 submission: the initial submission
		create table if not exists pull_submissions (
			-- identifiers
			id integer primary key autoincrement,
			pull_id integer not null,

			-- at identifiers
			repo_at text not null,

			-- content, these are immutable, and require a resubmission to update
			round_number integer not null default 0,
			patch text,

			-- meta
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),

			-- constraints
			unique(repo_at, pull_id, round_number),
			foreign key (repo_at, pull_id) references pulls(repo_at, pull_id) on delete cascade
		);

		create table if not exists pull_comments (
			-- identifiers
			id integer primary key autoincrement,
			pull_id integer not null,
			submission_id integer not null,

			-- at identifiers
			repo_at text not null,
			owner_did text not null,
			comment_at text not null,

			-- content
			body text not null,

			-- meta
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),

			-- constraints
			foreign key (repo_at, pull_id) references pulls(repo_at, pull_id) on delete cascade,
			foreign key (submission_id) references pull_submissions(id) on delete cascade
		);

		create table if not exists _jetstream (
			id integer primary key autoincrement,
			last_time_us integer not null
		);

		create table if not exists repo_issue_seqs (
			repo_at text primary key,
			next_issue_id integer not null default 1
		);

		create table if not exists repo_pull_seqs (
			repo_at text primary key,
			next_pull_id integer not null default 1
		);

		create table if not exists stars (
			id integer primary key autoincrement,
			starred_by_did text not null,
			repo_at text not null,
			rkey text not null,
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
			foreign key (repo_at) references repos(at_uri) on delete cascade,
			unique(starred_by_did, repo_at)
		);

		create table if not exists emails (
			id integer primary key autoincrement,
			did text not null,
			email text not null,
			verified integer not null default 0,
			verification_code text not null,
			last_sent text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
			is_primary integer not null default 0,
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
			unique(did, email)
		);

		create table if not exists artifacts (
			-- id
			id integer primary key autoincrement,
			did text not null,
			rkey text not null,

			-- meta
			repo_at text not null,
			tag binary(20) not null,
			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),

			-- data
			blob_cid text not null,
			name text not null,
			size integer not null default 0,
			mimetype string not null default "*/*",

			-- constraints
			unique(did, rkey),          -- record must be unique
			unique(repo_at, tag, name), -- for a given tag object, each file must be unique
			foreign key (repo_at) references repos(at_uri) on delete cascade
		);

		create table if not exists profile (
			-- id
			id integer primary key autoincrement,
			did text not null,

			-- data
			description text not null,
			include_bluesky integer not null default 0,
			location text,

			-- constraints
			unique(did)
		);
		create table if not exists profile_links (
			-- id
			id integer primary key autoincrement,
			did text not null,

			-- data
			link text not null,

			-- constraints
			foreign key (did) references profile(did) on delete cascade
		);
		create table if not exists profile_stats (
			-- id
			id integer primary key autoincrement,
			did text not null,

			-- data
			kind text not null check (kind in (
				"merged-pull-request-count",
				"closed-pull-request-count",
				"open-pull-request-count",
				"open-issue-count",
				"closed-issue-count",
				"repository-count"
			)),

			-- constraints
			foreign key (did) references profile(did) on delete cascade
		);
		create table if not exists profile_pinned_repositories (
			-- id
			id integer primary key autoincrement,
			did text not null,

			-- data
			at_uri text not null,

			-- constraints
			unique(did, at_uri),
			foreign key (did) references profile(did) on delete cascade,
			foreign key (at_uri) references repos(at_uri) on delete cascade
		);

		create table if not exists oauth_requests (
			id integer primary key autoincrement,
			auth_server_iss text not null,
			state text not null,
			did text not null,
			handle text not null,
			pds_url text not null,
			pkce_verifier text not null,
			dpop_auth_server_nonce text not null,
			dpop_private_jwk text not null
		);

		create table if not exists oauth_sessions (
			id integer primary key autoincrement,
			did text not null,
			handle text not null,
			pds_url text not null,
			auth_server_iss text not null,
			access_jwt text not null,
			refresh_jwt text not null,
			dpop_pds_nonce text,
			dpop_auth_server_nonce text not null,
			dpop_private_jwk text not null,
			expiry text not null
		);

		create table if not exists migrations (
			id integer primary key autoincrement,
			name text unique
		)
	`)
	if err != nil {
		return nil, err
	}

	// run migrations
	runMigration(db, "add-description-to-repos", func(tx *sql.Tx) error {
		tx.Exec(`
			alter table repos add column description text check (length(description) <= 200);
		`)
		return nil
	})

	runMigration(db, "add-rkey-to-pubkeys", func(tx *sql.Tx) error {
		// add unconstrained column
		_, err := tx.Exec(`
			alter table public_keys
			add column rkey text;
		`)
		if err != nil {
			return err
		}

		// backfill
		_, err = tx.Exec(`
			update public_keys
			set rkey = ''
			where rkey is null;
		`)
		if err != nil {
			return err
		}

		return nil
	})

	runMigration(db, "add-rkey-to-comments", func(tx *sql.Tx) error {
		_, err := tx.Exec(`
			alter table comments drop column comment_at;
			alter table comments add column rkey text;
		`)
		return err
	})

	runMigration(db, "add-deleted-and-edited-to-issue-comments", func(tx *sql.Tx) error {
		_, err := tx.Exec(`
			alter table comments add column deleted text; -- timestamp
			alter table comments add column edited text; -- timestamp
		`)
		return err
	})

	runMigration(db, "add-source-info-to-pulls-and-submissions", func(tx *sql.Tx) error {
		_, err := tx.Exec(`
			alter table pulls add column source_branch text;
			alter table pulls add column source_repo_at text;
			alter table pull_submissions add column source_rev text;
		`)
		return err
	})

	runMigration(db, "add-source-to-repos", func(tx *sql.Tx) error {
		_, err := tx.Exec(`
			alter table repos add column source text;
		`)
		return err
	})

	// disable foreign-keys for the next migration
	// NOTE: this cannot be done in a transaction, so it is run outside [0]
	//
	// [0]: https://sqlite.org/pragma.html#pragma_foreign_keys
	db.Exec("pragma foreign_keys = off;")
	runMigration(db, "recreate-pulls-column-for-stacking-support", func(tx *sql.Tx) error {
		_, err := tx.Exec(`
			create table pulls_new (
				-- identifiers
				id integer primary key autoincrement,
				pull_id integer not null,

				-- at identifiers
				repo_at text not null,
				owner_did text not null,
				rkey text not null,

				-- content
				title text not null,
				body text not null,
				target_branch text not null,
				state integer not null default 0 check (state in (0, 1, 2, 3)), -- closed, open, merged, deleted

				-- source info
				source_branch text,
				source_repo_at text,

				-- stacking
				stack_id text,
				change_id text,
				parent_change_id text,

				-- meta
				created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),

				-- constraints
				unique(repo_at, pull_id),
				foreign key (repo_at) references repos(at_uri) on delete cascade
			);

			insert into pulls_new (
				id, pull_id,
				repo_at, owner_did, rkey,
				title, body, target_branch, state,
				source_branch, source_repo_at,
				created
			)
			select
				id, pull_id,
				repo_at, owner_did, rkey,
				title, body, target_branch, state,
				source_branch, source_repo_at,
				created
			FROM pulls;

			drop table pulls;
			alter table pulls_new rename to pulls;
		`)
		return err
	})
	db.Exec("pragma foreign_keys = on;")

	return &DB{db}, nil
}

type migrationFn = func(*sql.Tx) error

func runMigration(d *sql.DB, name string, migrationFn migrationFn) error {
	tx, err := d.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	var exists bool
	err = tx.QueryRow("select exists (select 1 from migrations where name = ?)", name).Scan(&exists)
	if err != nil {
		return err
	}

	if !exists {
		// run migration
		err = migrationFn(tx)
		if err != nil {
			log.Printf("Failed to run migration %s: %v", name, err)
			return err
		}

		// mark migration as complete
		_, err = tx.Exec("insert into migrations (name) values (?)", name)
		if err != nil {
			log.Printf("Failed to mark migration %s as complete: %v", name, err)
			return err
		}

		// commit the transaction
		if err := tx.Commit(); err != nil {
			return err
		}

		log.Printf("migration %s applied successfully", name)
	} else {
		log.Printf("skipped migration %s, already applied", name)
	}

	return nil
}

type filter struct {
	key string
	arg any
	cmp string
}

func FilterEq(key string, arg any) filter {
	return filter{
		key: key,
		arg: arg,
		cmp: "=",
	}
}

func FilterNotEq(key string, arg any) filter {
	return filter{
		key: key,
		arg: arg,
		cmp: "<>",
	}
}

func (f filter) Condition() string {
	return fmt.Sprintf("%s %s ?", f.key, f.cmp)
}