package app

import (
	"context"
	"errors"
	"fmt"
	"sync"

	"gitea.maximumdirect.net/eric/weatherreporter/internal/comparison"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/promptdebug"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/promptexec"
)

type comparisonExecutionRequest struct {
	Prepared     preparedReport
	Inspection   ComparisonInspectionResult
	ComparisonID string
	DebugWriter  *promptdebug.PromptDebugWriter
	Executor     promptexec.Executor
}

type comparisonExecutionResult struct {
	Outcomes []comparisonProfileOutcome
	Canceled bool
}

type comparisonProfileOutcome struct {
	Position         int
	ProfileID        string
	BackendID        string
	ModelName        string
	Status           string
	ValidationStatus promptexec.ValidationStatus
	ReportPath       string
	Markdown         []byte
	LLMDebugPath     string
	Error            *comparison.SafeError
	canceled         bool
}

type comparisonProfileExecutionState uint8

const (
	comparisonProfilePending comparisonProfileExecutionState = iota
	comparisonProfileRunning
	comparisonProfileComplete
)

func executeComparisonProfiles(ctx context.Context, req comparisonExecutionRequest) comparisonExecutionResult {
	profiles := req.Inspection.Profiles
	result := comparisonExecutionResult{Outcomes: make([]comparisonProfileOutcome, len(profiles))}
	states := make([]comparisonProfileExecutionState, len(profiles))
	for index, profile := range profiles {
		result.Outcomes[index] = comparisonProfileOutcome{
			Position:  index + 1,
			ProfileID: profile.ProfileID,
			BackendID: profile.BackendID,
			ModelName: profile.ModelName,
			Status:    comparison.StatusFailed,
		}
	}

	var waitGroup sync.WaitGroup
	for index, profile := range profiles {
		if err := ctx.Err(); err != nil {
			result.Canceled = true
			break
		}
		index, profile := index, profile
		states[index] = comparisonProfileRunning
		waitGroup.Add(1)
		go func() {
			defer waitGroup.Done()
			result.Outcomes[index] = executeComparisonProfile(ctx, req, index, profile)
			states[index] = comparisonProfileComplete
		}()
	}
	waitGroup.Wait()
	if err := ctx.Err(); err != nil {
		result.Canceled = true
		for index := range result.Outcomes {
			if states[index] != comparisonProfileComplete || result.Outcomes[index].canceled {
				markCanceledComparisonOutcome(&result.Outcomes[index], err)
			}
		}
	}
	return result
}

func executeComparisonProfile(ctx context.Context, req comparisonExecutionRequest, index int, profile ComparisonProfileInspection) comparisonProfileOutcome {
	position := index + 1
	outcome := comparisonProfileOutcome{
		Position: position, ProfileID: profile.ProfileID, BackendID: profile.BackendID, ModelName: profile.ModelName,
		Status: comparison.StatusFailed,
	}
	debugRef := promptdebug.PromptDebugRef{
		ReportID:  req.Prepared.resolved.Definition.ID,
		ValidDate: req.Prepared.resolved.ValidPeriod.Start.Format("2006-01-02"),
		RunID:     comparisonDebugRunID(req.ComparisonID, position, len(req.Inspection.Profiles), profile.ProfileID),
	}
	execution, markdown, err := executePreparedProfile(ctx, profileExecutionRequest{
		Prepared: req.Prepared,
		Prompt: PromptInspectionResult{
			PromptID: req.Inspection.PromptID, PromptVersion: req.Inspection.PromptVersion, PromptHash: req.Inspection.PromptHash,
		},
		Profile:  promptexec.ProfileInspection{ProfileID: profile.ProfileID, BackendID: profile.BackendID, ModelName: profile.ModelName},
		Executor: req.Executor, DebugWriter: req.DebugWriter, DebugRef: &debugRef,
	})
	outcome.ProfileID, outcome.BackendID, outcome.ModelName = execution.ProfileID, execution.BackendID, execution.ModelName
	outcome.ValidationStatus = execution.ValidationStatus
	outcome.LLMDebugPath = execution.LLMDebugPath
	if err != nil {
		outcome.canceled = cancellationError(err)
		safe := comparisonSafeExecutionError(err)
		outcome.Error = &safe
		return outcome
	}
	reportPath, err := comparison.ReportFilename(position, len(req.Inspection.Profiles), profile.ProfileID)
	if err != nil {
		safe := comparison.NewSafeError("application", "derive comparison report filename failed")
		outcome.Error = &safe
		return outcome
	}
	outcome.Status = comparison.StatusSucceeded
	outcome.ReportPath = reportPath
	outcome.Markdown = append([]byte(nil), markdown...)
	return outcome
}

func comparisonDebugRunID(comparisonID string, position, profileCount int, profileID string) string {
	return fmt.Sprintf("%s_%0*d-%s", comparisonID, comparison.OrdinalWidth(profileCount), position, comparison.ProfileSlug(profileID))
}

func markCanceledComparisonOutcome(outcome *comparisonProfileOutcome, err error) {
	outcome.Status = comparison.StatusFailed
	outcome.ValidationStatus = promptexec.ValidationSkipped
	outcome.ReportPath = ""
	outcome.Markdown = nil
	safe := comparisonSafeExecutionError(err)
	outcome.Error = &safe
}

func cancellationError(err error) bool {
	category := promptexec.CategoryOf(err)
	return errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) ||
		category == promptexec.Canceled || category == promptexec.DeadlineExceeded
}

func comparisonSafeExecutionError(err error) comparison.SafeError {
	category := promptexec.CategoryOf(err)
	if category == "" {
		switch {
		case errors.Is(err, context.Canceled):
			category = promptexec.Canceled
		case errors.Is(err, context.DeadlineExceeded):
			category = promptexec.DeadlineExceeded
		}
	}
	if category == "" {
		return comparison.NewSafeError("application", comparisonExecutionMessage(err))
	}
	return comparison.NewSafeError(string(category), comparisonExecutionMessage(err))
}

func comparisonExecutionMessage(err error) string {
	if errors.Is(err, context.Canceled) {
		return "profile execution canceled"
	}
	if errors.Is(err, context.DeadlineExceeded) {
		return "profile execution deadline exceeded"
	}
	var execution *profileExecutionError
	if errors.As(err, &execution) {
		return comparison.TruncateErrorMessage(execution.operation + " failed")
	}
	return "profile execution failed"
}