// Package promptinput builds prompt data packages from briefing packages.
package promptinput

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/changes"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/forecast"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/report"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/timeutil"
)

const SchemaVersion = "weatherreporter.data_package.v1"

type Package struct {
	SchemaVersion  string                   `json:"schemaVersion"`
	RunID          string                   `json:"runId"`
	Report         Report                   `json:"report"`
	Briefing       briefing.Package         `json:"briefing"`
	RecentChanges  RecentChanges            `json:"recentChanges"`
	SourceWarnings []forecast.SourceWarning `json:"sourceWarnings,omitempty"`
}

type Report struct {
	ID          report.ID       `json:"id"`
	Variant     string          `json:"variant,omitempty"`
	PromptID    string          `json:"promptId"`
	GeneratedAt time.Time       `json:"generatedAt"`
	Timezone    string          `json:"timezone"`
	ValidPeriod timeutil.Period `json:"validPeriod"`
}

type RecentChanges struct {
	Items []changes.Change `json:"items"`
}

func Build(briefingPackage briefing.Package) (Package, error) {
	return BuildWithRecentChanges(briefingPackage, nil)
}

func BuildWithRecentChanges(briefingPackage briefing.Package, recentChanges []changes.Change) (Package, error) {
	items := make([]changes.Change, len(recentChanges))
	copy(items, recentChanges)
	if items == nil {
		items = []changes.Change{}
	}
	pkg := Package{
		SchemaVersion: SchemaVersion,
		RunID:         briefingPackage.Metadata.RunID,
		Report: Report{
			ID:          briefingPackage.Metadata.ReportID,
			Variant:     briefingPackage.Metadata.Variant,
			PromptID:    briefingPackage.Metadata.PromptID,
			GeneratedAt: briefingPackage.Metadata.GeneratedAt,
			Timezone:    briefingPackage.Metadata.Timezone,
			ValidPeriod: briefingPackage.Metadata.ValidPeriod,
		},
		Briefing:       briefingPackage,
		RecentChanges:  RecentChanges{Items: items},
		SourceWarnings: briefingPackage.Metadata.SourceWarnings,
	}
	if err := Validate(pkg); err != nil {
		return Package{}, err
	}
	return pkg, nil
}

func Validate(pkg Package) error {
	if pkg.SchemaVersion == "" {
		return fmt.Errorf("schemaVersion is required")
	}
	if pkg.RunID == "" {
		return fmt.Errorf("runId is required")
	}
	if pkg.Report.ID == "" {
		return fmt.Errorf("report.id is required")
	}
	if pkg.Report.PromptID == "" {
		return fmt.Errorf("report.promptId is required")
	}
	if pkg.Report.GeneratedAt.IsZero() {
		return fmt.Errorf("report.generatedAt is required")
	}
	if pkg.Report.Timezone == "" {
		return fmt.Errorf("report.timezone is required")
	}
	if !pkg.Report.ValidPeriod.IsValid() {
		return fmt.Errorf("report.validPeriod must be valid")
	}
	if pkg.Briefing.Metadata.RunID == "" {
		return fmt.Errorf("briefing.metadata.runId is required")
	}
	if pkg.Briefing.Metadata.RunID != pkg.RunID {
		return fmt.Errorf("briefing.metadata.runId must match runId")
	}
	if pkg.Briefing.Metadata.SchemaVersion == "" {
		return fmt.Errorf("briefing.metadata.schemaVersion is required")
	}
	if pkg.Briefing.Metadata.PromptID != pkg.Report.PromptID {
		return fmt.Errorf("briefing.metadata.promptId must match report.promptId")
	}
	if pkg.Briefing.Metadata.ReportID != pkg.Report.ID {
		return fmt.Errorf("briefing.metadata.reportId must match report.id")
	}
	if pkg.Briefing.Daily == nil && pkg.Briefing.ThreeDay == nil && pkg.Briefing.Weekend == nil && pkg.Briefing.Storm == nil {
		return fmt.Errorf("briefing report content is required")
	}
	return nil
}

func Save(path string, pkg Package) error {
	if err := Validate(pkg); err != nil {
		return err
	}
	data, err := json.MarshalIndent(pkg, "", "  ")
	if err != nil {
		return fmt.Errorf("marshal data package: %w", err)
	}
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return fmt.Errorf("create data package directory %q: %w", filepath.Dir(path), err)
	}
	tmp, err := os.CreateTemp(filepath.Dir(path), "."+filepath.Base(path)+".*.tmp")
	if err != nil {
		return fmt.Errorf("create temporary data package file: %w", err)
	}
	tmpName := tmp.Name()
	defer os.Remove(tmpName)

	if _, err := tmp.Write(data); err != nil {
		tmp.Close()
		return fmt.Errorf("write temporary data package file: %w", err)
	}
	if err := tmp.Close(); err != nil {
		return fmt.Errorf("close temporary data package file: %w", err)
	}
	if err := os.Rename(tmpName, path); err != nil {
		return fmt.Errorf("save data package %q: %w", path, err)
	}
	return nil
}