package message

import (
	"encoding/base64"
	"slices"
	"time"

	"github.com/sst/opencode/internal/llm/models"
)

type MessageRole string

const (
	Assistant MessageRole = "assistant"
	User      MessageRole = "user"
	System    MessageRole = "system"
	Tool      MessageRole = "tool"
)

type FinishReason string

const (
	FinishReasonEndTurn          FinishReason = "end_turn"
	FinishReasonMaxTokens        FinishReason = "max_tokens"
	FinishReasonToolUse          FinishReason = "tool_use"
	FinishReasonCanceled         FinishReason = "canceled"
	FinishReasonError            FinishReason = "error"
	FinishReasonPermissionDenied FinishReason = "permission_denied"

	// Should never happen
	FinishReasonUnknown FinishReason = "unknown"
)

type ContentPart interface {
	isPart()
}

type ReasoningContent struct {
	Thinking string `json:"thinking"`
}

func (tc ReasoningContent) String() string {
	return tc.Thinking
}
func (ReasoningContent) isPart() {}

type TextContent struct {
	Text string `json:"text"`
}

func (tc *TextContent) String() string {
	if tc == nil {
		return ""
	}
	return tc.Text
}

func (TextContent) isPart() {}

type ImageURLContent struct {
	URL    string `json:"url"`
	Detail string `json:"detail,omitempty"`
}

func (iuc ImageURLContent) String() string {
	return iuc.URL
}

func (ImageURLContent) isPart() {}

type BinaryContent struct {
	Path     string
	MIMEType string
	Data     []byte
}

func (bc BinaryContent) String(provider models.ModelProvider) string {
	base64Encoded := base64.StdEncoding.EncodeToString(bc.Data)
	if provider == models.ProviderOpenAI {
		return "data:" + bc.MIMEType + ";base64," + base64Encoded
	}
	return base64Encoded
}

func (BinaryContent) isPart() {}

type ToolCall struct {
	ID       string `json:"id"`
	Name     string `json:"name"`
	Input    string `json:"input"`
	Type     string `json:"type"`
	Finished bool   `json:"finished"`
}

func (ToolCall) isPart() {}

type ToolResult struct {
	ToolCallID string `json:"tool_call_id"`
	Name       string `json:"name"`
	Content    string `json:"content"`
	Metadata   string `json:"metadata"`
	IsError    bool   `json:"is_error"`
}

func (ToolResult) isPart() {}

type Finish struct {
	Reason FinishReason `json:"reason"`
	Time   time.Time    `json:"time"`
}

type DBFinish struct {
	Reason FinishReason `json:"reason"`
	Time   int64        `json:"time"`
}

func (Finish) isPart() {}

func (m *Message) Content() *TextContent {
	for _, part := range m.Parts {
		if c, ok := part.(TextContent); ok {
			return &c
		}
	}
	return nil
}

func (m *Message) ReasoningContent() ReasoningContent {
	for _, part := range m.Parts {
		if c, ok := part.(ReasoningContent); ok {
			return c
		}
	}
	return ReasoningContent{}
}

func (m *Message) ImageURLContent() []ImageURLContent {
	imageURLContents := make([]ImageURLContent, 0)
	for _, part := range m.Parts {
		if c, ok := part.(ImageURLContent); ok {
			imageURLContents = append(imageURLContents, c)
		}
	}
	return imageURLContents
}

func (m *Message) BinaryContent() []BinaryContent {
	binaryContents := make([]BinaryContent, 0)
	for _, part := range m.Parts {
		if c, ok := part.(BinaryContent); ok {
			binaryContents = append(binaryContents, c)
		}
	}
	return binaryContents
}

func (m *Message) ToolCalls() []ToolCall {
	toolCalls := make([]ToolCall, 0)
	for _, part := range m.Parts {
		if c, ok := part.(ToolCall); ok {
			toolCalls = append(toolCalls, c)
		}
	}
	return toolCalls
}

func (m *Message) ToolResults() []ToolResult {
	toolResults := make([]ToolResult, 0)
	for _, part := range m.Parts {
		if c, ok := part.(ToolResult); ok {
			toolResults = append(toolResults, c)
		}
	}
	return toolResults
}

func (m *Message) IsFinished() bool {
	for _, part := range m.Parts {
		if _, ok := part.(Finish); ok {
			return true
		}
	}
	return false
}

func (m *Message) FinishPart() *Finish {
	for _, part := range m.Parts {
		if c, ok := part.(Finish); ok {
			return &c
		}
	}
	return nil
}

func (m *Message) FinishReason() FinishReason {
	for _, part := range m.Parts {
		if c, ok := part.(Finish); ok {
			return c.Reason
		}
	}
	return ""
}

func (m *Message) IsThinking() bool {
	if m.ReasoningContent().Thinking != "" && m.Content().Text == "" && !m.IsFinished() {
		return true
	}
	return false
}

func (m *Message) AppendContent(delta string) {
	found := false
	for i, part := range m.Parts {
		if c, ok := part.(TextContent); ok {
			m.Parts[i] = TextContent{Text: c.Text + delta}
			found = true
		}
	}
	if !found {
		m.Parts = append(m.Parts, TextContent{Text: delta})
	}
}

func (m *Message) AppendReasoningContent(delta string) {
	found := false
	for i, part := range m.Parts {
		if c, ok := part.(ReasoningContent); ok {
			m.Parts[i] = ReasoningContent{Thinking: c.Thinking + delta}
			found = true
		}
	}
	if !found {
		m.Parts = append(m.Parts, ReasoningContent{Thinking: delta})
	}
}

func (m *Message) FinishToolCall(toolCallID string) {
	for i, part := range m.Parts {
		if c, ok := part.(ToolCall); ok {
			if c.ID == toolCallID {
				m.Parts[i] = ToolCall{
					ID:       c.ID,
					Name:     c.Name,
					Input:    c.Input,
					Type:     c.Type,
					Finished: true,
				}
				return
			}
		}
	}
}

func (m *Message) AppendToolCallInput(toolCallID string, inputDelta string) {
	for i, part := range m.Parts {
		if c, ok := part.(ToolCall); ok {
			if c.ID == toolCallID {
				m.Parts[i] = ToolCall{
					ID:       c.ID,
					Name:     c.Name,
					Input:    c.Input + inputDelta,
					Type:     c.Type,
					Finished: c.Finished,
				}
				return
			}
		}
	}
}

func (m *Message) AddToolCall(tc ToolCall) {
	for i, part := range m.Parts {
		if c, ok := part.(ToolCall); ok {
			if c.ID == tc.ID {
				m.Parts[i] = tc
				return
			}
		}
	}
	m.Parts = append(m.Parts, tc)
}

func (m *Message) SetToolCalls(tc []ToolCall) {
	// remove any existing tool call part it could have multiple
	parts := make([]ContentPart, 0)
	for _, part := range m.Parts {
		if _, ok := part.(ToolCall); ok {
			continue
		}
		parts = append(parts, part)
	}
	m.Parts = parts
	for _, toolCall := range tc {
		m.Parts = append(m.Parts, toolCall)
	}
}

func (m *Message) AddToolResult(tr ToolResult) {
	m.Parts = append(m.Parts, tr)
}

func (m *Message) SetToolResults(tr []ToolResult) {
	for _, toolResult := range tr {
		m.Parts = append(m.Parts, toolResult)
	}
}

func (m *Message) AddFinish(reason FinishReason) {
	// remove any existing finish part
	for i, part := range m.Parts {
		if _, ok := part.(Finish); ok {
			m.Parts = slices.Delete(m.Parts, i, i+1)
			break
		}
	}
	m.Parts = append(m.Parts, Finish{Reason: reason, Time: time.Now()})
}

func (m *Message) AddImageURL(url, detail string) {
	m.Parts = append(m.Parts, ImageURLContent{URL: url, Detail: detail})
}

func (m *Message) AddBinary(mimeType string, data []byte) {
	m.Parts = append(m.Parts, BinaryContent{MIMEType: mimeType, Data: data})
}