package generatedtext

import (
	"fmt"

	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/facts"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/module"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/promptassets"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/report"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/reporttemplate"
)

const (
	schemaIDHourly   = "hourly"
	schemaIDDaily    = "daily"
	schemaIDToday    = "today"
	schemaIDTomorrow = "tomorrow"

	templateIDHourly   = "hourly"
	templateIDDaily    = "daily"
	templateIDToday    = "today"
	templateIDTomorrow = "tomorrow"
)

type validator func([]byte) (any, []byte, error)

type renderContextBuilder func(report.ID, string, briefing.PreparedIdentity, module.Snapshot, facts.DerivedFacts, any) (any, error)

type catalogEntry struct {
	reportID             report.ID
	schemaID             string
	templateID           string
	validate             validator
	renderContextBuilder renderContextBuilder
}

type Handler struct {
	reportID             report.ID
	schemaID             string
	templateID           string
	validate             validator
	renderContextBuilder renderContextBuilder
}

var catalog = []catalogEntry{
	{
		reportID:             report.Hourly,
		schemaID:             schemaIDHourly,
		templateID:           templateIDHourly,
		validate:             validateHourly,
		renderContextBuilder: buildHourlyContext,
	},
	{
		reportID:             report.Daily,
		schemaID:             schemaIDDaily,
		templateID:           templateIDDaily,
		validate:             validateDaily,
		renderContextBuilder: buildDailyContext,
	},
	{
		reportID:             report.Today,
		schemaID:             schemaIDToday,
		templateID:           templateIDToday,
		validate:             validateToday,
		renderContextBuilder: buildTodayContext,
	},
	{
		reportID:             report.Tomorrow,
		schemaID:             schemaIDTomorrow,
		templateID:           templateIDTomorrow,
		validate:             validateTomorrow,
		renderContextBuilder: buildTomorrowContext,
	},
}

func LookupDefinition(definition report.Definition) (Handler, error) {
	var schemaKnown, templateKnown, pairKnown bool
	for _, entry := range catalog {
		if entry.schemaID == definition.GeneratedTextSchemaID {
			schemaKnown = true
		}
		if entry.templateID == definition.TemplateID {
			templateKnown = true
		}
		if entry.schemaID == definition.GeneratedTextSchemaID && entry.templateID == definition.TemplateID {
			pairKnown = true
			if entry.reportID != definition.ID {
				continue
			}
			return Handler{
				reportID:             entry.reportID,
				schemaID:             entry.schemaID,
				templateID:           entry.templateID,
				validate:             entry.validate,
				renderContextBuilder: entry.renderContextBuilder,
			}, nil
		}
	}
	if !schemaKnown {
		return Handler{}, fmt.Errorf("generated text schema %q is not supported for report %q", definition.GeneratedTextSchemaID, definition.ID)
	}
	if !templateKnown {
		return Handler{}, fmt.Errorf("report template %q is not supported for report %q", definition.TemplateID, definition.ID)
	}
	if pairKnown {
		return Handler{}, fmt.Errorf("generated text schema %q and report template %q do not belong to report %q", definition.GeneratedTextSchemaID, definition.TemplateID, definition.ID)
	}
	return Handler{}, fmt.Errorf("generated text schema %q and report template %q are not supported together for report %q", definition.GeneratedTextSchemaID, definition.TemplateID, definition.ID)
}

func (h Handler) SchemaID() string {
	return h.schemaID
}

func (h Handler) TemplateID() string {
	return h.templateID
}

func (h Handler) Schema() ([]byte, error) {
	data, err := promptassets.Schema(h.schemaID)
	if err != nil {
		return nil, fmt.Errorf("load generated text schema %q for report %q: %w", h.schemaID, h.reportID, err)
	}
	return data, nil
}

func (h Handler) Template() (string, error) {
	source, err := reporttemplate.Template(h.templateID)
	if err != nil {
		return "", fmt.Errorf("load report template %q for report %q: %w", h.templateID, h.reportID, err)
	}
	return source, nil
}

func (h Handler) Validate(data []byte) (any, []byte, error) {
	if h.validate == nil {
		return nil, nil, fmt.Errorf("generated text validator is not registered for schema %q on report %q", h.schemaID, h.reportID)
	}
	return h.validate(data)
}

func (h Handler) BuildRenderContext(identity briefing.PreparedIdentity, snapshot module.Snapshot, derived facts.DerivedFacts, generated any) (any, error) {
	if h.renderContextBuilder == nil {
		return nil, fmt.Errorf("render-context builder is not registered for template %q on report %q", h.templateID, h.reportID)
	}
	return h.renderContextBuilder(h.reportID, h.templateID, identity, snapshot, derived, generated)
}

func (h Handler) Render(data any) ([]byte, error) {
	rendered, err := reporttemplate.Render(h.templateID, data)
	if err != nil {
		return nil, fmt.Errorf("render report template %q for report %q: %w", h.templateID, h.reportID, err)
	}
	return rendered, nil
}

func validateHourly(data []byte) (any, []byte, error) {
	return ValidateHourly(data)
}

func validateDaily(data []byte) (any, []byte, error) {
	return ValidateDaily(data)
}

func validateToday(data []byte) (any, []byte, error) {
	return ValidateToday(data)
}

func validateTomorrow(data []byte) (any, []byte, error) {
	return ValidateTomorrow(data)
}

func buildHourlyContext(reportID report.ID, templateID string, identity briefing.PreparedIdentity, snapshot module.Snapshot, _ facts.DerivedFacts, generated any) (any, error) {
	hourly, ok := generated.(Hourly)
	if !ok {
		return nil, fmt.Errorf("report template %q requires hourly generated text for report %q", templateID, reportID)
	}
	return BuildHourlyRenderContext(identity, snapshot, hourly)
}

func buildDailyContext(reportID report.ID, templateID string, identity briefing.PreparedIdentity, snapshot module.Snapshot, derived facts.DerivedFacts, generated any) (any, error) {
	daily, ok := generated.(Daily)
	if !ok {
		return nil, fmt.Errorf("report template %q requires daily generated text for report %q", templateID, reportID)
	}
	return BuildDailyRenderContext(identity, snapshot, daily, derived)
}

func buildTodayContext(reportID report.ID, templateID string, identity briefing.PreparedIdentity, snapshot module.Snapshot, derived facts.DerivedFacts, generated any) (any, error) {
	today, ok := generated.(Today)
	if !ok {
		return nil, fmt.Errorf("report template %q requires today generated text for report %q", templateID, reportID)
	}
	return BuildTodayRenderContext(identity, snapshot, today, derived)
}

func buildTomorrowContext(reportID report.ID, templateID string, identity briefing.PreparedIdentity, snapshot module.Snapshot, derived facts.DerivedFacts, generated any) (any, error) {
	tomorrow, ok := generated.(Tomorrow)
	if !ok {
		return nil, fmt.Errorf("report template %q requires tomorrow generated text for report %q", templateID, reportID)
	}
	return BuildTomorrowRenderContext(identity, snapshot, tomorrow, derived)
}