package pgdump

import (
	"context"
	"fmt"
	"io"
	"os"
	"os/exec"
	"strings"

	"git.tswf.io/infra/go-synapse-backupper/pkg/domain/pgdump"
)

// adapter provides pg_dump functionality using the system's pg_dump binary.
type adapter struct {
	commandContext func(ctx context.Context, name string, arg ...string) *exec.Cmd
}

// New creates a new pg_dump adapter.
func New() pgdump.Dumper {
	return &adapter{
		commandContext: exec.CommandContext,
	}
}

// Dump executes pg_dump and writes the output to sink.
func (a *adapter) Dump(
	ctx context.Context,
	opts pgdump.Options,
	sink io.Writer,
) (retErr error) {
	defer func() {
		if pipeWriter, ok := sink.(*io.PipeWriter); ok {
			if retErr != nil {
				_ = pipeWriter.CloseWithError(retErr)
			} else {
				_ = pipeWriter.Close()
			}
		}
	}()

	args := buildArgs(opts)

	cmd := a.commandContext(ctx, "pg_dump", args...)

	env := os.Environ()
	if opts.Password != "" {
		env = append(env, fmt.Sprintf("PGPASSWORD=%s", opts.Password))
	}
	if opts.Host != "" {
		env = append(env, fmt.Sprintf("PGHOST=%s", opts.Host))
	}
	if opts.Port != 0 {
		env = append(env, fmt.Sprintf("PGPORT=%d", opts.Port))
	}
	if opts.User != "" {
		env = append(env, fmt.Sprintf("PGUSER=%s", opts.User))
	}
	if opts.Database != "" {
		env = append(env, fmt.Sprintf("PGDATABASE=%s", opts.Database))
	}
	cmd.Env = env

	var stderrBuilder strings.Builder
	cmd.Stderr = &stderrBuilder
	cmd.Stdout = sink

	runErr := cmd.Run()
	stderr := strings.TrimSpace(stderrBuilder.String())

	if runErr != nil {
		if exitErr, ok := runErr.(*exec.ExitError); ok {
			return fmt.Errorf("%w (exit %d): %s", pgdump.ErrPgDumpFailed(exitErr.ExitCode()), exitErr.ExitCode(), stderr)
		}
		return runErr
	}

	if cmd.ProcessState.ExitCode() != 0 {
		return fmt.Errorf("%w (exit %d): %s", pgdump.ErrPgDumpFailed(cmd.ProcessState.ExitCode()), cmd.ProcessState.ExitCode(), stderr)
	}

	return nil
}

func buildArgs(opts pgdump.Options) []string {
	excludeTables := opts.ExcludeTables
	if len(excludeTables) == 0 {
		excludeTables = make([]string, 1)
		excludeTables[0] = "e2e_one_time_keys_json"
	}

	args := make([]string, 0, len(excludeTables)+1)
	args = append(args, "--format=custom")

	for _, table := range excludeTables {
		args = append(args, "--exclude-table="+table)
	}

	return args
}