package csharp

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

	"github.com/ricarneiro/ctx/internal/output"
	"github.com/ricarneiro/ctx/internal/plugins/csharp/helper"
)

// WriteSummary formats a ProjectSummary as dense markdown.
func WriteSummary(w io.Writer, s *helper.ProjectSummary) error {
	output.H1(w, "Solution: "+s.SolutionName)
	writeOverview(w, s)
	output.H2(w, "Projects")
	writeProjects(w, s.Projects)
	writeReferenceGraph(w, s.Projects)
	writeMultiTargeting(w, s.Projects)
	return nil
}

func writeOverview(w io.Writer, s *helper.ProjectSummary) {
	exeCount, libCount := 0, 0
	totalDocs := 0
	for _, p := range s.Projects {
		if p.Type == "exe" {
			exeCount++
		} else {
			libCount++
		}
		totalDocs += p.DocumentCount
	}

	projectSummary := fmt.Sprintf("%d", len(s.Projects))
	parts := []string{}
	if exeCount > 0 {
		parts = append(parts, fmt.Sprintf("%d exe", exeCount))
	}
	if libCount > 0 {
		parts = append(parts, fmt.Sprintf("%d lib", libCount))
	}
	if len(parts) > 0 {
		projectSummary += " (" + strings.Join(parts, ", ") + ")"
	}

	output.KeyValue(w, "path", "`"+s.SolutionPath+"`")
	output.KeyValue(w, "projects", projectSummary)
	output.KeyValue(w, "documents", fmt.Sprintf("%d", totalDocs))
	fmt.Fprintln(w)
}

func writeProjects(w io.Writer, projects []helper.ProjectInfo) {
	for _, p := range projects {
		output.H3(w, fmt.Sprintf("%s (%s)", p.Name, p.Type))

		fmt.Fprintf(w, "- **path:** `%s`\n", p.Path)

		targets := strings.Join(p.TargetFrameworks, ", ")
		if targets == "" {
			targets = "_(unknown)_"
		}
		fmt.Fprintf(w, "- **target:** %s\n", targets)
		fmt.Fprintf(w, "- **namespace:** `%s`\n", p.RootNamespace)
		fmt.Fprintf(w, "- **documents:** %d\n", p.DocumentCount)

		// Project references
		if len(p.ProjectReferences) == 0 {
			fmt.Fprintf(w, "- **references:** _(none)_\n")
		} else {
			refs := make([]string, len(p.ProjectReferences))
			for i, r := range p.ProjectReferences {
				refs[i] = "`" + r + "`"
			}
			fmt.Fprintf(w, "- **references:**\n")
			for _, r := range refs {
				fmt.Fprintf(w, "  - %s\n", r)
			}
		}

		// Package references
		if len(p.PackageReferences) == 0 {
			fmt.Fprintf(w, "- **packages:** _(none)_\n")
		} else {
			pkgs := make([]string, len(p.PackageReferences))
			for i, pkg := range p.PackageReferences {
				pkgs[i] = pkg.Name + " " + pkg.Version
			}
			fmt.Fprintf(w, "- **packages:** %s\n", strings.Join(pkgs, ", "))
		}

		fmt.Fprintln(w)
	}
}

func writeReferenceGraph(w io.Writer, projects []helper.ProjectInfo) {
	// Build reverse dependency map: who depends on each project
	dependents := map[string][]string{}
	refMap := map[string][]string{}
	nameSet := map[string]bool{}

	for _, p := range projects {
		nameSet[p.Name] = true
		refMap[p.Name] = p.ProjectReferences
		for _, ref := range p.ProjectReferences {
			dependents[ref] = append(dependents[ref], p.Name)
		}
	}

	// Check if there are any references at all
	hasRefs := false
	for _, p := range projects {
		if len(p.ProjectReferences) > 0 {
			hasRefs = true
			break
		}
	}

	output.H2(w, "Reference graph")

	if !hasRefs {
		fmt.Fprintf(w, "No inter-project references.\n\n")
		return
	}

	// For complex graphs (>5 projects with references), use flat list
	refsCount := 0
	for _, p := range projects {
		if len(p.ProjectReferences) > 0 {
			refsCount++
		}
	}

	if len(projects) > 5 && refsCount > 3 {
		for _, p := range projects {
			if len(p.ProjectReferences) > 0 {
				refs := make([]string, len(p.ProjectReferences))
				for i, r := range p.ProjectReferences {
					refs[i] = "`" + r + "`"
				}
				fmt.Fprintf(w, "- `%s` → %s\n", p.Name, strings.Join(refs, ", "))
			}
		}
		fmt.Fprintln(w)
		return
	}

	// DFS from roots (projects with no dependents)
	roots := []string{}
	for _, p := range projects {
		if len(dependents[p.Name]) == 0 {
			roots = append(roots, p.Name)
		}
	}

	if len(roots) == 0 {
		// Cycle or all have dependents — fall back to flat list
		for _, p := range projects {
			if len(p.ProjectReferences) > 0 {
				refs := make([]string, len(p.ProjectReferences))
				for i, r := range p.ProjectReferences {
					refs[i] = "`" + r + "`"
				}
				fmt.Fprintf(w, "- `%s` → %s\n", p.Name, strings.Join(refs, ", "))
			}
		}
		fmt.Fprintln(w)
		return
	}

	var sb strings.Builder
	visited := map[string]bool{}
	for _, root := range roots {
		dfsRender(&sb, root, refMap, visited, 0)
	}
	output.CodeBlock(w, "", strings.TrimRight(sb.String(), "\n"))
}

func dfsRender(sb *strings.Builder, name string, refMap map[string][]string, visited map[string]bool, depth int) {
	indent := strings.Repeat("  ", depth)
	refs := refMap[name]
	if len(refs) == 0 {
		if depth == 0 {
			fmt.Fprintf(sb, "%s%s (no deps)\n", indent, name)
		} else {
			fmt.Fprintf(sb, "%s%s\n", indent, name)
		}
		return
	}

	if visited[name] {
		fmt.Fprintf(sb, "%s%s (see above)\n", indent, name)
		return
	}
	visited[name] = true

	for i, ref := range refs {
		if i == 0 {
			fmt.Fprintf(sb, "%s%s → %s\n", indent, name, ref)
		} else {
			fmt.Fprintf(sb, "%s%s   └──→ %s\n", indent, strings.Repeat(" ", len(name)), ref)
		}
		dfsRender(sb, ref, refMap, visited, depth+1)
	}
}

func writeMultiTargeting(w io.Writer, projects []helper.ProjectInfo) {
	output.H2(w, "Multi-targeting")

	// Collect all unique frameworks
	frameworkSets := map[string][]string{} // project name → frameworks
	allFrameworks := map[string]bool{}

	for _, p := range projects {
		if len(p.TargetFrameworks) > 1 {
			frameworkSets[p.Name] = p.TargetFrameworks
		}
		for _, tf := range p.TargetFrameworks {
			allFrameworks[tf] = true
		}
	}

	if len(frameworkSets) == 0 {
		// All same framework, or single framework each
		switch len(allFrameworks) {
		case 0:
			fmt.Fprintf(w, "No target frameworks detected.\n\n")
		case 1:
			for tf := range allFrameworks {
				fmt.Fprintf(w, "None — all projects target `%s`.\n\n", tf)
			}
		default:
			// Multiple different single targets
			for _, p := range projects {
				if len(p.TargetFrameworks) > 0 {
					fmt.Fprintf(w, "- `%s` targets: `%s`\n", p.Name, strings.Join(p.TargetFrameworks, "`, `"))
				}
			}
			fmt.Fprintln(w)
		}
		return
	}

	for _, p := range projects {
		if tfs, ok := frameworkSets[p.Name]; ok {
			fmt.Fprintf(w, "- `%s` targets: `%s`\n", p.Name, strings.Join(tfs, "`, `"))
		}
	}
	fmt.Fprintln(w)
}

// ─── Outline formatter ───────────────────────────────────────────────────────

// WriteOutline formats an OutlineResult as dense markdown.
func WriteOutline(w io.Writer, o *helper.OutlineResult) error {
	fileName := filepath.Base(o.Path)
	output.H1(w, "Outline: "+fileName)

	if o.HasSyntaxErrors {
		fmt.Fprintf(w, "> ⚠️ File has syntax errors — outline may be incomplete.\n\n")
	}

	// Overview
	typeSummary := outlineTypesSummary(o.Types)
	output.KeyValue(w, "path", "`"+o.Path+"`")
	if o.Namespace != "" {
		output.KeyValue(w, "namespace", "`"+o.Namespace+"`")
	}
	output.KeyValue(w, "lines", fmt.Sprintf("%d", o.LineCount))
	output.KeyValue(w, "types", typeSummary)
	fmt.Fprintln(w)

	// Usings
	if len(o.Usings) > 0 {
		output.H2(w, "Usings")
		for _, u := range o.Usings {
			fmt.Fprintf(w, "- `%s`\n", u)
		}
		fmt.Fprintln(w)
	}

	// Types
	if len(o.Types) > 0 {
		output.H2(w, "Types")
		for i := range o.Types {
			writeOutlineType(w, &o.Types[i], 3)
		}
	}

	return nil
}

func outlineTypesSummary(types []helper.OutlineType) string {
	counts := map[string]int{}
	for _, t := range types {
		counts[t.Kind]++
	}
	if len(counts) == 0 {
		return "none"
	}
	// Fixed display order
	order := []string{"class", "interface", "struct", "record", "record struct", "enum"}
	parts := []string{}
	for _, k := range order {
		if n, ok := counts[k]; ok {
			parts = append(parts, fmt.Sprintf("%d %s", n, k))
			delete(counts, k)
		}
	}
	// Any remaining unknown kinds
	for k, n := range counts {
		parts = append(parts, fmt.Sprintf("%d %s", n, k))
	}
	return strings.Join(parts, ", ")
}

func writeOutlineType(w io.Writer, t *helper.OutlineType, headingLevel int) {
	// Build header: `kind Name : Base1, Base2` (modifiers)
	header := t.Kind + " " + t.Name
	if len(t.BaseTypes) > 0 {
		header += " : " + strings.Join(t.BaseTypes, ", ")
	}
	heading := "`" + header + "`"
	if len(t.Modifiers) > 0 {
		heading += " (" + strings.Join(t.Modifiers, ", ") + ")"
	}
	writeHeading(w, headingLevel, heading)

	// Group members by kind, in canonical order
	writeOutlineMembers(w, t.Members, headingLevel+1)

	// Nested types — shown as bullet list for simplicity
	if len(t.Nested) > 0 {
		writeHeading(w, headingLevel+1, "Nested types")
		for _, n := range t.Nested {
			nestedHeader := n.Kind + " " + n.Name
			if len(n.BaseTypes) > 0 {
				nestedHeader += " : " + strings.Join(n.BaseTypes, ", ")
			}
			prefix := modPrefix(n.Modifiers)
			fmt.Fprintf(w, "- `%s%s`\n", prefix, nestedHeader)
		}
		fmt.Fprintln(w)
	}
}

func writeOutlineMembers(w io.Writer, members []helper.OutlineMember, headingLevel int) {
	// Collect by kind
	var fields, constructors, properties, methods, events []helper.OutlineMember
	for _, m := range members {
		switch m.Kind {
		case "field":
			fields = append(fields, m)
		case "constructor":
			constructors = append(constructors, m)
		case "property":
			properties = append(properties, m)
		case "method":
			methods = append(methods, m)
		case "event":
			events = append(events, m)
		}
	}

	if len(fields) > 0 {
		writeHeading(w, headingLevel, "Fields")
		for _, m := range fields {
			writeMemberLine(w, m)
		}
		fmt.Fprintln(w)
	}
	if len(constructors) > 0 {
		writeHeading(w, headingLevel, "Constructor")
		for _, m := range constructors {
			writeMemberLine(w, m)
		}
		fmt.Fprintln(w)
	}
	if len(properties) > 0 {
		writeHeading(w, headingLevel, "Properties")
		for _, m := range properties {
			writeMemberLine(w, m)
		}
		fmt.Fprintln(w)
	}
	if len(methods) > 0 {
		writeHeading(w, headingLevel, "Methods")
		for _, m := range methods {
			writeMemberLine(w, m)
		}
		fmt.Fprintln(w)
	}
	if len(events) > 0 {
		writeHeading(w, headingLevel, "Events")
		for _, m := range events {
			writeMemberLine(w, m)
		}
		fmt.Fprintln(w)
	}
}

func writeMemberLine(w io.Writer, m helper.OutlineMember) {
	prefix := modPrefix(m.Modifiers)
	obsolete := ""
	if m.IsObsolete {
		obsolete = " _(obsolete)_"
	}
	lineRef := ""
	if m.Line > 0 {
		lineRef = fmt.Sprintf(" (line %d)", m.Line)
	}
	fmt.Fprintf(w, "- `%s%s`%s%s\n", prefix, m.Signature, lineRef, obsolete)
}

func modPrefix(mods []string) string {
	if len(mods) == 0 {
		return ""
	}
	return strings.Join(mods, " ") + " "
}

func writeHeading(w io.Writer, level int, text string) {
	fmt.Fprintf(w, "%s %s\n\n", strings.Repeat("#", level), text)
}