package speaker

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"gopkg.in/yaml.v3"
)

// Map resolves input file basenames to canonical speaker names.
type Map struct {
	inputs map[string]Input
}

// Input describes one input entry in speakers.yml.
type Input struct {
	Speaker string `yaml:"speaker"`
}

type fileSchema struct {
	Inputs map[string]Input `yaml:"inputs"`
}

// LoadMap parses a speakers.yml file.
func LoadMap(path string) (Map, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return Map{}, err
	}

	var parsed fileSchema
	if err := yaml.Unmarshal(data, &parsed); err != nil {
		return Map{}, fmt.Errorf("parse speaker map %q: %w", path, err)
	}
	if len(parsed.Inputs) == 0 {
		return Map{}, fmt.Errorf("speaker map %q must contain at least one inputs entry", path)
	}

	inputs := make(map[string]Input, len(parsed.Inputs))
	for key, input := range parsed.Inputs {
		basename := filepath.Base(strings.TrimSpace(key))
		if basename == "." || basename == "" {
			return Map{}, fmt.Errorf("speaker map %q contains an empty input key", path)
		}
		if _, exists := inputs[basename]; exists {
			return Map{}, fmt.Errorf("speaker map %q contains duplicate basename mapping for %q", path, basename)
		}

		input.Speaker = strings.TrimSpace(input.Speaker)
		if input.Speaker == "" {
			return Map{}, fmt.Errorf("speaker map entry %q must include speaker", basename)
		}
		inputs[basename] = input
	}

	return Map{inputs: inputs}, nil
}

// SpeakerForSource returns the canonical speaker for a transcript source path.
func (m Map) SpeakerForSource(source string) (string, error) {
	basename := filepath.Base(source)
	input, ok := m.inputs[basename]
	if !ok {
		return "", fmt.Errorf("speaker map has no entry for input basename %q", basename)
	}
	return input.Speaker, nil
}